An error occurred fetching the project authors.
- 04 Aug, 2023 1 commit
-
-
Miaohe Lin authored
Patch series "A few fixup patches for mm", v2. This series contains a few fixup patches to fix potential unexpected return value, fix wrong swap entry type for hwpoisoned swapcache page and so on. More details can be found in the respective changelogs. This patch (of 3): Hwpoisoned dirty swap cache page is kept in the swap cache and there's simple interception code in do_swap_page() to catch it. But when trying to swapoff, unuse_pte() will wrongly install a general sense of "future accesses are invalid" swap entry for hwpoisoned swap cache page due to unaware of such type of page. The user will receive SIGBUS signal without expected BUS_MCEERR_AR payload. BTW, typo 'hwposioned' is fixed. Link: https://lkml.kernel.org/r/20230727115643.639741-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20230727115643.639741-2-linmiaohe@huawei.com Fixes: 6b970599 ("mm: hwpoison: support recovery from ksm_might_need_to_copy()") Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 23 Jun, 2023 1 commit
-
-
Matthew Wilcox (Oracle) authored
Most of these should just refer to the LRU cache rather than the data structure used to implement the LRU cache. Link: https://lkml.kernel.org/r/20230621164557.3510324-13-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 19 Jun, 2023 3 commits
-
-
Ryan Roberts authored
Convert all instances of direct pte_t* dereferencing to instead use ptep_get() helper. This means that by default, the accesses change from a C dereference to a READ_ONCE(). This is technically the correct thing to do since where pgtables are modified by HW (for access/dirty) they are volatile and therefore we should always ensure READ_ONCE() semantics. But more importantly, by always using the helper, it can be overridden by the architecture to fully encapsulate the contents of the pte. Arch code is deliberately not converted, as the arch code knows best. It is intended that arch code (arm64) will override the default with its own implementation that can (e.g.) hide certain bits from the core code, or determine young/dirty status by mixing in state from another source. Conversion was done using Coccinelle: ---- // $ make coccicheck \ // COCCI=ptepget.cocci \ // SPFLAGS="--include-headers" \ // MODE=patch virtual patch @ depends on patch @ pte_t *v; @@ - *v + ptep_get(v) ---- Then reviewed and hand-edited to avoid multiple unnecessary calls to ptep_get(), instead opting to store the result of a single call in a variable, where it is correct to do so. This aims to negate any cost of READ_ONCE() and will benefit arch-overrides that may be more complex. Included is a fix for an issue in an earlier version of this patch that was pointed out by kernel test robot. The issue arose because config MMU=n elides definition of the ptep helper functions, including ptep_get(). HUGETLB_PAGE=n configs still define a simple huge_ptep_clear_flush() for linking purposes, which dereferences the ptep. So when both configs are disabled, this caused a build error because ptep_get() is not defined. Fix by continuing to do a direct dereference when MMU=n. This is safe because for this config the arch code cannot be trying to virtualize the ptes because none of the ptep helpers are defined. Link: https://lkml.kernel.org/r/20230612151545.3317766-4-ryan.roberts@arm.comReported-by: kernel test robot <lkp@intel.com> Link: https://lore.kernel.org/oe-kbuild-all/202305120142.yXsNEo6H-lkp@intel.com/Signed-off-by: Ryan Roberts <ryan.roberts@arm.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Potapenko <glider@google.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Alex Williamson <alex.williamson@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Christian Brauner <brauner@kernel.org> Cc: Christoph Hellwig <hch@infradead.org> Cc: Daniel Vetter <daniel@ffwll.ch> Cc: Dave Airlie <airlied@gmail.com> Cc: Dimitri Sivanich <dimitri.sivanich@hpe.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Ian Rogers <irogers@google.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: SeongJae Park <sj@kernel.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Uladzislau Rezki (Sony) <urezki@gmail.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Yu Zhao <yuzhao@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
Hugh Dickins authored
Following the examples of nearby code, various functions can just give up if pte_offset_map() or pte_offset_map_lock() fails. And there's no need for a preliminary pmd_trans_unstable() or other such check, since such cases are now safely handled inside. Link: https://lkml.kernel.org/r/7b9bd85d-1652-cbf2-159d-f503b45e5b@google.comSigned-off-by: Hugh Dickins <hughd@google.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Christoph Hellwig <hch@infradead.org> Cc: David Hildenbrand <david@redhat.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Peter Xu <peterx@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: SeongJae Park <sj@kernel.org> Cc: Song Liu <song@kernel.org> Cc: Steven Price <steven.price@arm.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com> Cc: Will Deacon <will@kernel.org> Cc: Yang Shi <shy828301@gmail.com> Cc: Yu Zhao <yuzhao@google.com> Cc: Zack Rusin <zackr@vmware.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
Hugh Dickins authored
Patch series "mm: allow pte_offset_map[_lock]() to fail", v2. What is it all about? Some mmap_lock avoidance i.e. latency reduction. Initially just for the case of collapsing shmem or file pages to THPs; but likely to be relied upon later in other contexts e.g. freeing of empty page tables (but that's not work I'm doing). mmap_write_lock avoidance when collapsing to anon THPs? Perhaps, but again that's not work I've done: a quick attempt was not as easy as the shmem/file case. I would much prefer not to have to make these small but wide-ranging changes for such a niche case; but failed to find another way, and have heard that shmem MADV_COLLAPSE's usefulness is being limited by that mmap_write_lock it currently requires. These changes (though of course not these exact patches) have been in Google's data centre kernel for three years now: we do rely upon them. What is this preparatory series about? The current mmap locking will not be enough to guard against that tricky transition between pmd entry pointing to page table, and empty pmd entry, and pmd entry pointing to huge page: pte_offset_map() will have to validate the pmd entry for itself, returning NULL if no page table is there. What to do about that varies: sometimes nearby error handling indicates just to skip it; but in many cases an ACTION_AGAIN or "goto again" is appropriate (and if that risks an infinite loop, then there must have been an oops, or pfn 0 mistaken for page table, before). Given the likely extension to freeing empty page tables, I have not limited this set of changes to a THP config; and it has been easier, and sets a better example, if each site is given appropriate handling: even where deeper study might prove that failure could only happen if the pmd table were corrupted. Several of the patches are, or include, cleanup on the way; and by the end, pmd_trans_unstable() and suchlike are deleted: pte_offset_map() and pte_offset_map_lock() then handle those original races and more. Most uses of pte_lockptr() are deprecated, with pte_offset_map_nolock() taking its place. This patch (of 32): Use pmdp_get_lockless() in preference to READ_ONCE(*pmdp), to get a more reliable result with PAE (or READ_ONCE as before without PAE); and remove the unnecessary extra barrier()s which got left behind in its callers. HOWEVER: Note the small print in linux/pgtable.h, where it was designed specifically for fast GUP, and depends on interrupts being disabled for its full guarantee: most callers which have been added (here and before) do NOT have interrupts disabled, so there is still some need for caution. Link: https://lkml.kernel.org/r/f35279a9-9ac0-de22-d245-591afbfb4dc@google.comSigned-off-by: Hugh Dickins <hughd@google.com> Acked-by: Yu Zhao <yuzhao@google.com> Acked-by: Peter Xu <peterx@redhat.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Christoph Hellwig <hch@infradead.org> Cc: David Hildenbrand <david@redhat.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lorenzo Stoakes <lstoakes@gmail.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport (IBM) <rppt@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Pavel Tatashin <pasha.tatashin@soleen.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: SeongJae Park <sj@kernel.org> Cc: Song Liu <song@kernel.org> Cc: Steven Price <steven.price@arm.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com> Cc: Will Deacon <will@kernel.org> Cc: Yang Shi <shy828301@gmail.com> Cc: Zack Rusin <zackr@vmware.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 03 May, 2023 2 commits
-
-
David Hildenbrand authored
Let's factor out actual disabling of KSM. The existing "mm->def_flags &= ~VM_MERGEABLE;" was essentially a NOP and can be dropped, because def_flags should never include VM_MERGEABLE. Note that we don't currently prevent re-enabling KSM. This should now be faster in case KSM was never enabled, because we only conditionally iterate all VMAs. Further, it certainly looks cleaner. Link: https://lkml.kernel.org/r/20230422210156.33630-1-david@redhat.comSigned-off-by: David Hildenbrand <david@redhat.com> Acked-by: Janosch Frank <frankja@linux.ibm.com> Acked-by: Stefan Roesch <shr@devkernel.io> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Claudio Imbrenda <imbrenda@linux.ibm.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Rik van Riel <riel@surriel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
David Hildenbrand authored
Patch series "mm/ksm: improve PR_SET_MEMORY_MERGE=0 handling and cleanup disabling KSM", v2. (1) Make PR_SET_MEMORY_MERGE=0 unmerge pages like setting MADV_UNMERGEABLE does, (2) add a selftest for it and (3) factor out disabling of KSM from s390/gmap code. This patch (of 3): Let's unmerge any KSM pages when setting PR_SET_MEMORY_MERGE=0, and clear the VM_MERGEABLE flag from all VMAs -- just like KSM would. Of course, only do that if we previously set PR_SET_MEMORY_MERGE=1. Link: https://lkml.kernel.org/r/20230422205420.30372-1-david@redhat.com Link: https://lkml.kernel.org/r/20230422205420.30372-2-david@redhat.comSigned-off-by: David Hildenbrand <david@redhat.com> Acked-by: Stefan Roesch <shr@devkernel.io> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Claudio Imbrenda <imbrenda@linux.ibm.com> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Janosch Frank <frankja@linux.ibm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Rik van Riel <riel@surriel.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 21 Apr, 2023 2 commits
-
-
Stefan Roesch authored
This adds the general_profit KSM sysfs knob and the process profit metric knobs to ksm_stat. 1) expose general_profit metric The documentation mentions a general profit metric, however this metric is not calculated. In addition the formula depends on the size of internal structures, which makes it more difficult for an administrator to make the calculation. Adding the metric for a better user experience. 2) document general_profit sysfs knob 3) calculate ksm process profit metric The ksm documentation mentions the process profit metric and how to calculate it. This adds the calculation of the metric. 4) mm: expose ksm process profit metric in ksm_stat This exposes the ksm process profit metric in /proc/<pid>/ksm_stat. The documentation mentions the formula for the ksm process profit metric, however it does not calculate it. In addition the formula depends on the size of internal structures. So it makes sense to expose it. 5) document new procfs ksm knobs Link: https://lkml.kernel.org/r/20230418051342.1919757-3-shr@devkernel.ioSigned-off-by: Stefan Roesch <shr@devkernel.io> Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: David Hildenbrand <david@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
Stefan Roesch authored
Patch series "mm: process/cgroup ksm support", v9. So far KSM can only be enabled by calling madvise for memory regions. To be able to use KSM for more workloads, KSM needs to have the ability to be enabled / disabled at the process / cgroup level. Use case 1: The madvise call is not available in the programming language. An example for this are programs with forked workloads using a garbage collected language without pointers. In such a language madvise cannot be made available. In addition the addresses of objects get moved around as they are garbage collected. KSM sharing needs to be enabled "from the outside" for these type of workloads. Use case 2: The same interpreter can also be used for workloads where KSM brings no benefit or even has overhead. We'd like to be able to enable KSM on a workload by workload basis. Use case 3: With the madvise call sharing opportunities are only enabled for the current process: it is a workload-local decision. A considerable number of sharing opportunities may exist across multiple workloads or jobs (if they are part of the same security domain). Only a higler level entity like a job scheduler or container can know for certain if its running one or more instances of a job. That job scheduler however doesn't have the necessary internal workload knowledge to make targeted madvise calls. Security concerns: In previous discussions security concerns have been brought up. The problem is that an individual workload does not have the knowledge about what else is running on a machine. Therefore it has to be very conservative in what memory areas can be shared or not. However, if the system is dedicated to running multiple jobs within the same security domain, its the job scheduler that has the knowledge that sharing can be safely enabled and is even desirable. Performance: Experiments with using UKSM have shown a capacity increase of around 20%. Here are the metrics from an instagram workload (taken from a machine with 64GB main memory): full_scans: 445 general_profit: 20158298048 max_page_sharing: 256 merge_across_nodes: 1 pages_shared: 129547 pages_sharing: 5119146 pages_to_scan: 4000 pages_unshared: 1760924 pages_volatile: 10761341 run: 1 sleep_millisecs: 20 stable_node_chains: 167 stable_node_chains_prune_millisecs: 2000 stable_node_dups: 2751 use_zero_pages: 0 zero_pages_sharing: 0 After the service is running for 30 minutes to an hour, 4 to 5 million shared pages are common for this workload when using KSM. Detailed changes: 1. New options for prctl system command This patch series adds two new options to the prctl system call. The first one allows to enable KSM at the process level and the second one to query the setting. The setting will be inherited by child processes. With the above setting, KSM can be enabled for the seed process of a cgroup and all processes in the cgroup will inherit the setting. 2. Changes to KSM processing When KSM is enabled at the process level, the KSM code will iterate over all the VMA's and enable KSM for the eligible VMA's. When forking a process that has KSM enabled, the setting will be inherited by the new child process. 3. Add general_profit metric The general_profit metric of KSM is specified in the documentation, but not calculated. This adds the general profit metric to /sys/kernel/debug/mm/ksm. 4. Add more metrics to ksm_stat This adds the process profit metric to /proc/<pid>/ksm_stat. 5. Add more tests to ksm_tests and ksm_functional_tests This adds an option to specify the merge type to the ksm_tests. This allows to test madvise and prctl KSM. It also adds a two new tests to ksm_functional_tests: one to test the new prctl options and the other one is a fork test to verify that the KSM process setting is inherited by client processes. This patch (of 3): So far KSM can only be enabled by calling madvise for memory regions. To be able to use KSM for more workloads, KSM needs to have the ability to be enabled / disabled at the process / cgroup level. 1. New options for prctl system command This patch series adds two new options to the prctl system call. The first one allows to enable KSM at the process level and the second one to query the setting. The setting will be inherited by child processes. With the above setting, KSM can be enabled for the seed process of a cgroup and all processes in the cgroup will inherit the setting. 2. Changes to KSM processing When KSM is enabled at the process level, the KSM code will iterate over all the VMA's and enable KSM for the eligible VMA's. When forking a process that has KSM enabled, the setting will be inherited by the new child process. 1) Introduce new MMF_VM_MERGE_ANY flag This introduces the new flag MMF_VM_MERGE_ANY flag. When this flag is set, kernel samepage merging (ksm) gets enabled for all vma's of a process. 2) Setting VM_MERGEABLE on VMA creation When a VMA is created, if the MMF_VM_MERGE_ANY flag is set, the VM_MERGEABLE flag will be set for this VMA. 3) support disabling of ksm for a process This adds the ability to disable ksm for a process if ksm has been enabled for the process with prctl. 4) add new prctl option to get and set ksm for a process This adds two new options to the prctl system call - enable ksm for all vmas of a process (if the vmas support it). - query if ksm has been enabled for a process. 3. Disabling MMF_VM_MERGE_ANY for storage keys in s390 In the s390 architecture when storage keys are used, the MMF_VM_MERGE_ANY will be disabled. Link: https://lkml.kernel.org/r/20230418051342.1919757-1-shr@devkernel.io Link: https://lkml.kernel.org/r/20230418051342.1919757-2-shr@devkernel.ioSigned-off-by: Stefan Roesch <shr@devkernel.io> Acked-by: David Hildenbrand <david@redhat.com> Cc: David Hildenbrand <david@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Rik van Riel <riel@surriel.com> Cc: Bagas Sanjaya <bagasdotme@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 18 Apr, 2023 1 commit
-
-
Longlong Xia authored
hwpoison_user_mappings() is updated to support ksm pages, and add collect_procs_ksm() to collect processes when the error hit an ksm page. The difference from collect_procs_anon() is that it also needs to traverse the rmap-item list on the stable node of the ksm page. At the same time, add_to_kill_ksm() is added to handle ksm pages. And task_in_to_kill_list() is added to avoid duplicate addition of tsk to the to_kill list. This is because when scanning the list, if the pages that make up the ksm page all come from the same process, they may be added repeatedly. Link: https://lkml.kernel.org/r/20230414021741.2597273-3-xialonglong1@huawei.comSigned-off-by: Longlong Xia <xialonglong1@huawei.com> Tested-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Nanyong Sun <sunnanyong@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 28 Mar, 2023 1 commit
-
-
Stefan Roesch authored
This adds the following tracepoints to ksm: - start / stop scan - ksm enter / exit - merge a page - merge a page with ksm - remove a page - remove a rmap item This patch has been split off from the RFC patch series "mm: process/cgroup ksm support". Link: https://lkml.kernel.org/r/20230210214645.2720847-1-shr@devkernel.ioSigned-off-by: Stefan Roesch <shr@devkernel.io> Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 24 Mar, 2023 1 commit
-
-
Liam R. Howlett authored
exit_mmap() will tear down the VMAs and maple tree with the mmap_lock held in write mode. Ensure that the maple tree is still valid by checking ksm_test_exit() after taking the mmap_lock in read mode, but before the for_each_vma() iterator dereferences a destroyed maple tree. Since the maple tree is destroyed, the flags telling lockdep to check an external lock has been cleared. Skip the for_each_vma() iterator to avoid dereferencing a maple tree without the external lock flag, which would create a lockdep warning. Link: https://lkml.kernel.org/r/20230308220310.3119196-1-Liam.Howlett@oracle.com Fixes: a5f18ba0 ("mm/ksm: use vma iterators instead of vma linked list") Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com> Reported-by: Pengfei Xu <pengfei.xu@intel.com> Link: https://lore.kernel.org/lkml/ZAdUUhSbaa6fHS36@xpf.sh.intel.com/ Reported-by: syzbot+2ee18845e89ae76342c5@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?id=64a3e95957cd3deab99df7cd7b5a9475af92c93eAcked-by: David Hildenbrand <david@redhat.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: <heng.su@intel.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 09 Feb, 2023 1 commit
-
-
Kefeng Wang authored
When the kernel copies a page from ksm_might_need_to_copy(), but runs into an uncorrectable error, it will crash since poisoned page is consumed by kernel, this is similar to the issue recently fixed by Copy-on-write poison recovery. When an error is detected during the page copy, return VM_FAULT_HWPOISON in do_swap_page(), and install a hwpoison entry in unuse_pte() when swapoff, which help us to avoid system crash. Note, memory failure on a KSM page will be skipped, but still call memory_failure_queue() to be consistent with general memory failure process, and we could support KSM page recovery in the feature. [wangkefeng.wang@huawei.com: enhance unuse_pte(), fix issue found by lkp] Link: https://lkml.kernel.org/r/20221213120523.141588-1-wangkefeng.wang@huawei.com [wangkefeng.wang@huawei.com: update changelog, alter ksm_might_need_to_copy(), restore unlikely() in unuse_pte()] Link: https://lkml.kernel.org/r/20230201074433.96641-1-wangkefeng.wang@huawei.com Link: https://lkml.kernel.org/r/20221209072801.193221-1-wangkefeng.wang@huawei.comSigned-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Tony Luck <tony.luck@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 03 Feb, 2023 1 commit
-
-
Alistair Popple authored
mmu_notifier_range_update_to_read_only() was originally introduced in commit c6d23413 ("mm/mmu_notifier: mmu_notifier_range_update_to_read_only() helper") as an optimisation for device drivers that know a range has only been mapped read-only. However there are no users of this feature so remove it. As it is the only user of the struct mmu_notifier_range.vma field remove that also. Link: https://lkml.kernel.org/r/20230110025722.600912-1-apopple@nvidia.comSigned-off-by: Alistair Popple <apopple@nvidia.com> Acked-by: Mike Rapoport (IBM) <rppt@kernel.org> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Ira Weiny <ira.weiny@intel.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Ralph Campbell <rcampbell@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 12 Dec, 2022 3 commits
-
-
David Hildenbrand authored
FOLL_MIGRATION exists only for the purpose of break_ksm(), and actually, there is not even the need to wait for the migration to finish, we only want to know if we're dealing with a KSM page. Using follow_page() just to identify a KSM page overcomplicates GUP code. Let's use walk_page_range_vma() instead, because we don't actually care about the page itself, we only need to know a single property -- no need to even grab a reference. So, get rid of follow_page() usage such that we can get rid of FOLL_MIGRATION now and eventually be able to get rid of follow_page() in the future. In my setup (AMD Ryzen 9 3900X), running the KSM selftest to test unmerge performance on 2 GiB (taskset 0x8 ./ksm_tests -D -s 2048), this results in a performance degradation of ~2% (old: ~5010 MiB/s, new: ~4900 MiB/s). I don't think we particularly care for now. Interestingly, the benchmark reduction is due to the single callback. Adding a second callback (e.g., pud_entry()) reduces the benchmark by another 100-200 MiB/s. Link: https://lkml.kernel.org/r/20221021101141.84170-9-david@redhat.comSigned-off-by: David Hildenbrand <david@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Peter Xu <peterx@redhat.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
David Hildenbrand authored
Let's stop breaking COW via a fake write fault and let's use FAULT_FLAG_UNSHARE instead. This avoids any wrong side effects of the fake write fault, such as mapping the PTE writable and marking the pte dirty/softdirty. Consequently, we will no longer trigger a fake write fault and break COW without any such side-effects. Also, this fixes KSM interaction with userfaultfd-wp: when we have a KSM page that's write-protected by userfaultfd, break_ksm()->handle_mm_fault() will fail with VM_FAULT_SIGBUS and will simply return in break_ksm() with 0 instead of actually breaking COW. For now, the KSM unmerge tests can trigger that: $ sudo ./ksm_functional_tests TAP version 13 1..3 # [RUN] test_unmerge ok 1 Pages were unmerged # [RUN] test_unmerge_discarded ok 2 Pages were unmerged # [RUN] test_unmerge_uffd_wp not ok 3 Pages were unmerged Bail out! 1 out of 3 tests failed # Planned tests != run tests (2 != 3) # Totals: pass:2 fail:1 xfail:0 xpass:0 skip:0 error:0 The warning in dmesg also indicates this wrong handling: [ 230.096368] FAULT_FLAG_ALLOW_RETRY missing 881 [ 230.100822] CPU: 1 PID: 1643 Comm: ksm-uffd-wp [...] [ 230.110124] Hardware name: [...] [ 230.117775] Call Trace: [ 230.120227] <TASK> [ 230.122334] dump_stack_lvl+0x44/0x5c [ 230.126010] handle_userfault.cold+0x14/0x19 [ 230.130281] ? tlb_finish_mmu+0x65/0x170 [ 230.134207] ? uffd_wp_range+0x65/0xa0 [ 230.137959] ? _raw_spin_unlock+0x15/0x30 [ 230.141972] ? do_wp_page+0x50/0x590 [ 230.145551] __handle_mm_fault+0x9f5/0xf50 [ 230.149652] ? mmput+0x1f/0x40 [ 230.152712] handle_mm_fault+0xb9/0x2a0 [ 230.156550] break_ksm+0x141/0x180 [ 230.159964] unmerge_ksm_pages+0x60/0x90 [ 230.163890] ksm_madvise+0x3c/0xb0 [ 230.167295] do_madvise.part.0+0x10c/0xeb0 [ 230.171396] ? do_syscall_64+0x67/0x80 [ 230.175157] __x64_sys_madvise+0x5a/0x70 [ 230.179082] do_syscall_64+0x58/0x80 [ 230.182661] ? do_syscall_64+0x67/0x80 [ 230.186413] entry_SYSCALL_64_after_hwframe+0x63/0xcd This is primarily a fix for KSM+userfaultfd-wp, however, the fake write fault was always questionable. As this fix is not easy to backport and it's not very critical, let's not cc stable. Link: https://lkml.kernel.org/r/20221021101141.84170-6-david@redhat.com Fixes: 529b930b ("userfaultfd: wp: hook userfault handler to write protection fault") Signed-off-by: David Hildenbrand <david@redhat.com> Acked-by: Peter Xu <peterx@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Shuah Khan <shuah@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
David Hildenbrand authored
Now that GUP no longer requires VM_FAULT_WRITE, break_ksm() is the sole remaining user of VM_FAULT_WRITE. As we also want to stop triggering a fake write fault and instead use FAULT_FLAG_UNSHARE -- similar to GUP-triggered unsharing when taking a R/O pin on a shared anonymous page (including KSM pages), let's stop relying on VM_FAULT_WRITE. Let's rework break_ksm() to not rely on the return value of handle_mm_fault() anymore to figure out whether COW-breaking was successful. Simply perform another follow_page() lookup to verify the result. While this makes break_ksm() slightly less efficient, we can simplify handle_mm_fault() a little and easily switch to FAULT_FLAG_UNSHARE without introducing similar KSM-specific behavior for FAULT_FLAG_UNSHARE. In my setup (AMD Ryzen 9 3900X), running the KSM selftest to test unmerge performance on 2 GiB (taskset 0x8 ./ksm_tests -D -s 2048), this results in a performance degradation of ~4% -- 5% (old: ~5250 MiB/s, new: ~5010 MiB/s). I don't think that we particularly care about that performance drop when unmerging. If it ever turns out to be an actual performance issue, we can think about a better alternative for FAULT_FLAG_UNSHARE -- let's just keep it simple for now. Link: https://lkml.kernel.org/r/20221021101141.84170-3-david@redhat.comSigned-off-by: David Hildenbrand <david@redhat.com> Acked-by: Peter Xu <peterx@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Shuah Khan <shuah@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 30 Nov, 2022 1 commit
-
-
David Hildenbrand authored
commit b191f9b1 ("mm: numa: preserve PTE write permissions across a NUMA hinting fault") added remembering write permissions using ordinary pte_write() for PROT_NONE mapped pages to avoid write faults when remapping the page !PROT_NONE on NUMA hinting faults. That commit noted: The patch looks hacky but the alternatives looked worse. The tidest was to rewalk the page tables after a hinting fault but it was more complex than this approach and the performance was worse. It's not generally safe to just mark the page writable during the fault if it's a write fault as it may have been read-only for COW so that approach was discarded. Later, commit 288bc549 ("mm/autonuma: let architecture override how the write bit should be stashed in a protnone pte.") introduced a family of savedwrite PTE functions that didn't necessarily improve the whole situation. One confusing thing is that nowadays, if a page is pte_protnone() and pte_savedwrite() then also pte_write() is true. Another source of confusion is that there is only a single pte_mk_savedwrite() call in the kernel. All other write-protection code seems to silently rely on pte_wrprotect(). Ever since PageAnonExclusive was introduced and we started using it in mprotect context via commit 64fe24a3 ("mm/mprotect: try avoiding write faults for exclusive anonymous pages when changing protection"), we do have machinery in place to avoid write faults when changing protection, which is exactly what we want to do here. Let's similarly do what ordinary mprotect() does nowadays when upgrading write permissions and reuse can_change_pte_writable() and can_change_pmd_writable() to detect if we can upgrade PTE permissions to be writable. For anonymous pages there should be absolutely no change: if an anonymous page is not exclusive, it could not have been mapped writable -- because only exclusive anonymous pages can be mapped writable. However, there *might* be a change for writable shared mappings that require writenotify: if they are not dirty, we cannot map them writable. While it might not matter in practice, we'd need a different way to identify whether writenotify is actually required -- and ordinary mprotect would benefit from that as well. Note that we don't optimize for the actual migration case: (1) When migration succeeds the new PTE will not be writable because the source PTE was not writable (protnone); in the future we might just optimize that case similarly by reusing can_change_pte_writable()/can_change_pmd_writable() when removing migration PTEs. (2) When migration fails, we'd have to recalculate the "writable" flag because we temporarily dropped the PT lock; for now keep it simple and set "writable=false". We'll remove all savedwrite leftovers next. Link: https://lkml.kernel.org/r/20221108174652.198904-6-david@redhat.comSigned-off-by: David Hildenbrand <david@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Dave Chinner <david@fromorbit.com> Cc: Hugh Dickins <hughd@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Mike Rapoport <rppt@kernel.org> Cc: Nadav Amit <namit@vmware.com> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 09 Nov, 2022 1 commit
-
-
Liu Shixin authored
The priority of hotplug memory callback is defined in a different file. And there are some callers using numbers directly. Collect them together into include/linux/memory.h for easy reading. This allows us to sort their priorities more intuitively without additional comments. Link: https://lkml.kernel.org/r/20220923033347.3935160-9-liushixin2@huawei.comSigned-off-by: Liu Shixin <liushixin2@huawei.com> Cc: Christoph Lameter <cl@linux.com> Cc: David Hildenbrand <david@redhat.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Waiman Long <longman@redhat.com> Cc: zefan li <lizefan.x@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 03 Oct, 2022 5 commits
-
-
Matthew Wilcox (Oracle) authored
Replace three calls to compound_head() with one. Link: https://lkml.kernel.org/r/20220902194653.1739778-46-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
Qi Zheng authored
Convert to use common struct mm_slot, no functional change. Link: https://lkml.kernel.org/r/20220831031951.43152-8-zhengqi.arch@bytedance.comSigned-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
Qi Zheng authored
In order to use common struct mm_slot, convert ksm_mm_slot.link to ksm_mm_slot.hash in advance, no functional change. Link: https://lkml.kernel.org/r/20220831031951.43152-7-zhengqi.arch@bytedance.comSigned-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
Qi Zheng authored
In order to use common struct mm_slot, convert ksm_mm_slot.mm_list to ksm_mm_slot.mm_node in advance, no functional change. Link: https://lkml.kernel.org/r/20220831031951.43152-6-zhengqi.arch@bytedance.comSigned-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
Qi Zheng authored
In order to prevent the name of the private structure of ksm from being the same as the name of the common structure used in subsequent patches, prefix their names with ksm in advance. Link: https://lkml.kernel.org/r/20220831031951.43152-5-zhengqi.arch@bytedance.comSigned-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mike Rapoport <rppt@kernel.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 27 Sep, 2022 3 commits
-
-
xu xin authored
Patch series "ksm: count allocated rmap_items and update documentation", v5. KSM can save memory by merging identical pages, but also can consume additional memory, because it needs to generate rmap_items to save each scanned page's brief rmap information. To determine how beneficial the ksm-policy (like madvise), they are using brings, so we add a new interface /proc/<pid>/ksm_stat for each process The value "ksm_rmap_items" in it indicates the total allocated ksm rmap_items of this process. The detailed description can be seen in the following patches' commit message. This patch (of 2): KSM can save memory by merging identical pages, but also can consume additional memory, because it needs to generate rmap_items to save each scanned page's brief rmap information. Some of these pages may be merged, but some may not be abled to be merged after being checked several times, which are unprofitable memory consumed. The information about whether KSM save memory or consume memory in system-wide range can be determined by the comprehensive calculation of pages_sharing, pages_shared, pages_unshared and pages_volatile. A simple approximate calculation: profit =~ pages_sharing * sizeof(page) - (all_rmap_items) * sizeof(rmap_item); where all_rmap_items equals to the sum of pages_sharing, pages_shared, pages_unshared and pages_volatile. But we cannot calculate this kind of ksm profit inner single-process wide because the information of ksm rmap_item's number of a process is lacked. For user applications, if this kind of information could be obtained, it helps upper users know how beneficial the ksm-policy (like madvise) they are using brings, and then optimize their app code. For example, one application madvise 1000 pages as MERGEABLE, while only a few pages are really merged, then it's not cost-efficient. So we add a new interface /proc/<pid>/ksm_stat for each process in which the value of ksm_rmap_itmes is only shown now and so more values can be added in future. So similarly, we can calculate the ksm profit approximately for a single process by: profit =~ ksm_merging_pages * sizeof(page) - ksm_rmap_items * sizeof(rmap_item); where ksm_merging_pages is shown at /proc/<pid>/ksm_merging_pages, and ksm_rmap_items is shown in /proc/<pid>/ksm_stat. Link: https://lkml.kernel.org/r/20220830143731.299702-1-xu.xin16@zte.com.cn Link: https://lkml.kernel.org/r/20220830143838.299758-1-xu.xin16@zte.com.cnSigned-off-by: xu xin <xu.xin16@zte.com.cn> Reviewed-by: Xiaokai Ran <ran.xiaokai@zte.com.cn> Reviewed-by: Yang Yang <yang.yang29@zte.com.cn> Signed-off-by: CGEL ZTE <cgel.zte@gmail.com> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Bagas Sanjaya <bagasdotme@gmail.com> Cc: Hugh Dickins <hughd@google.com> Cc: Izik Eidus <izik.eidus@ravellosystems.com> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
Haiyue Wang authored
The handling Non-LRU pages returned by follow_page() jumps directly, it doesn't call put_page() to handle the reference count, since 'FOLL_GET' flag for follow_page() has get_page() called. Fix the zone device page check by handling the page reference count correctly before returning. And as David reviewed, "device pages are never PageKsm pages". Drop this zone device page check for break_ksm(). Since the zone device page can't be a transparent huge page, so drop the redundant zone device page check for split_huge_pages_pid(). (by Miaohe) Link: https://lkml.kernel.org/r/20220823135841.934465-3-haiyue.wang@intel.com Fixes: 3218f871 ("mm: handling Non-LRU pages returned by vm_normal_pages") Signed-off-by: Haiyue Wang <haiyue.wang@intel.com> Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com> Reviewed-by: Alistair Popple <apopple@nvidia.com> Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> Acked-by: David Hildenbrand <david@redhat.com> Cc: Alex Sierra <alex.sierra@amd.com> Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
Matthew Wilcox (Oracle) authored
Remove the use of the linked list for eventual removal. Link: https://lkml.kernel.org/r/20220906194824.2110408-54-Liam.Howlett@oracle.comSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net> Tested-by: Yu Zhao <yuzhao@google.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: David Hildenbrand <david@redhat.com> Cc: David Howells <dhowells@redhat.com> Cc: SeongJae Park <sj@kernel.org> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 12 Sep, 2022 2 commits
-
-
David Hildenbrand authored
commit 6c287605 ("mm: remember exclusively mapped anonymous pages with PG_anon_exclusive") made sure that when PageAnonExclusive() has to be cleared during temporary unmapping of a page, that the PTE is cleared/invalidated and that the TLB is flushed. What we want to achieve in all cases is that we cannot end up with a pin on an anonymous page that may be shared, because such pins would be unreliable and could result in memory corruptions when the mapped page and the pin go out of sync due to a write fault. That TLB flush handling was inspired by an outdated comment in mm/ksm.c:write_protect_page(), which similarly required the TLB flush in the past to synchronize with GUP-fast. However, ever since general RCU GUP fast was introduced in commit 2667f50e ("mm: introduce a general RCU get_user_pages_fast()"), a TLB flush is no longer sufficient to handle concurrent GUP-fast in all cases -- it only handles traditional IPI-based GUP-fast correctly. Peter Xu (thankfully) questioned whether that TLB flush is really required. On architectures that send an IPI broadcast on TLB flush, it works as expected. To synchronize with RCU GUP-fast properly, we're conceptually fine, however, we have to enforce a certain memory order and are missing memory barriers. Let's document that, avoid the TLB flush where possible and use proper explicit memory barriers where required. We shouldn't really care about the additional memory barriers here, as we're not on extremely hot paths -- and we're getting rid of some TLB flushes. We use a smp_mb() pair for handling concurrent pinning and a smp_rmb()/smp_wmb() pair for handling the corner case of only temporary PTE changes but permanent PageAnonExclusive changes. One extreme example, whereby GUP-fast takes a R/O pin and KSM wants to convert an exclusive anonymous page to a KSM page, and that page is already mapped write-protected (-> no PTE change) would be: Thread 0 (KSM) Thread 1 (GUP-fast) (B1) Read the PTE # (B2) skipped without FOLL_WRITE (A1) Clear PTE smp_mb() (A2) Check pinned (B3) Pin the mapped page smp_mb() (A3) Clear PageAnonExclusive smp_wmb() (A4) Restore PTE (B4) Check if the PTE changed smp_rmb() (B5) Check PageAnonExclusive Thread 1 will properly detect that PageAnonExclusive was cleared and back off. Note that we don't need a memory barrier between checking if the page is pinned and clearing PageAnonExclusive, because stores are not speculated. The possible issues due to reordering are of theoretical nature so far and attempts to reproduce the race failed. Especially the "no PTE change" case isn't the common case, because we'd need an exclusive anonymous page that's mapped R/O and the PTE is clean in KSM code -- and using KSM with page pinning isn't extremely common. Further, the clear+TLB flush we used for now implies a memory barrier. So the problematic missing part should be the missing memory barrier after pinning but before checking if the PTE changed. Link: https://lkml.kernel.org/r/20220901083559.67446-1-david@redhat.com Fixes: 6c287605 ("mm: remember exclusively mapped anonymous pages with PG_anon_exclusive") Signed-off-by: David Hildenbrand <david@redhat.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Peter Xu <peterx@redhat.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Nadav Amit <namit@vmware.com> Cc: Yang Shi <shy828301@gmail.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Andrea Parri <parri.andrea@gmail.com> Cc: Will Deacon <will@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Christoph von Recklinghausen <crecklin@redhat.com> Cc: Don Dutile <ddutile@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
Zach O'Keefe authored
When scanning an anon pmd to see if it's eligible for collapse, return SCAN_PMD_MAPPED if the pmd already maps a hugepage. Note that SCAN_PMD_MAPPED is different from SCAN_PAGE_COMPOUND used in the file-collapse path, since the latter might identify pte-mapped compound pages. This is required by MADV_COLLAPSE which necessarily needs to know what hugepage-aligned/sized regions are already pmd-mapped. In order to determine if a pmd already maps a hugepage, refactor mm_find_pmd(): Return mm_find_pmd() to it's pre-commit f72e7dcd ("mm: let mm_find_pmd fix buggy race with THP fault") behavior. ksm was the only caller that explicitly wanted a pte-mapping pmd, so open code the pte-mapping logic there (pmd_present() and pmd_trans_huge() checks). Undo revert change in commit f72e7dcd ("mm: let mm_find_pmd fix buggy race with THP fault") that open-coded split_huge_pmd_address() pmd lookup and use mm_find_pmd() instead. Link: https://lkml.kernel.org/r/20220706235936.2197195-9-zokeefe@google.comSigned-off-by: Zach O'Keefe <zokeefe@google.com> Reviewed-by: Yang Shi <shy828301@gmail.com> Cc: Alex Shi <alex.shi@linux.alibaba.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Chris Kennelly <ckennelly@google.com> Cc: Chris Zankel <chris@zankel.net> Cc: David Hildenbrand <david@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Helge Deller <deller@gmx.de> Cc: Hugh Dickins <hughd@google.com> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Matt Turner <mattst88@gmail.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Pavel Begunkov <asml.silence@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com> Cc: SeongJae Park <sj@kernel.org> Cc: Song Liu <songliubraving@fb.com> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <ziy@nvidia.com> Cc: Dan Carpenter <dan.carpenter@oracle.com> Cc: "Souptick Joarder (HPE)" <jrdr.linux@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 02 Aug, 2022 1 commit
-
-
Matthew Wilcox (Oracle) authored
migrate_page_move_mapping(), migrate_page_copy() and migrate_page_states() are all now unused after converting all the filesystems from aops->migratepage() to aops->migrate_folio(). Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org> Reviewed-by: Christoph Hellwig <hch@lst.de>
-
- 18 Jul, 2022 1 commit
-
-
Alex Sierra authored
With DEVICE_COHERENT, we'll soon have vm_normal_pages() return device-managed anonymous pages that are not LRU pages. Although they behave like normal pages for purposes of mapping in CPU page, and for COW. They do not support LRU lists, NUMA migration or THP. Callers to follow_page() currently don't expect ZONE_DEVICE pages, however, with DEVICE_COHERENT we might now return ZONE_DEVICE. Check for ZONE_DEVICE pages in applicable users of follow_page() as well. Link: https://lkml.kernel.org/r/20220715150521.18165-5-alex.sierra@amd.comSigned-off-by: Alex Sierra <alex.sierra@amd.com> Acked-by: Felix Kuehling <Felix.Kuehling@amd.com> [v2] Reviewed-by: Alistair Popple <apopple@nvidia.com> [v6] Cc: Christoph Hellwig <hch@lst.de> Cc: David Hildenbrand <david@redhat.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Ralph Campbell <rcampbell@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 27 Jun, 2022 1 commit
-
-
Mike Rapoport authored
so it will be consistent with code mm directory and with Documentation/admin-guide/mm and won't be confused with virtual machines. Signed-off-by: Mike Rapoport <rppt@linux.ibm.com> Suggested-by: Matthew Wilcox <willy@infradead.org> Tested-by: Ira Weiny <ira.weiny@intel.com> Acked-by: Jonathan Corbet <corbet@lwn.net> Acked-by: Wu XiangCheng <bobwxc@email.cn>
-
- 25 May, 2022 1 commit
-
-
Julia Lawall authored
Spelling mistake (triple letters) in comment. Detected with the help of Coccinelle. Link: https://lkml.kernel.org/r/20220521111145.81697-94-Julia.Lawall@inria.frSigned-off-by: Julia Lawall <Julia.Lawall@inria.fr> Reviewed-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 19 May, 2022 1 commit
-
-
Minchan Kim authored
The rmap locks(i_mmap_rwsem and anon_vma->root->rwsem) could be contended under memory pressure if processes keep working on their vmas(e.g., fork, mmap, munmap). It makes reclaim path stuck. In our real workload traces, we see kswapd is waiting the lock for 300ms+(worst case, a sec) and it makes other processes entering direct reclaim, which were also stuck on the lock. This patch makes lru aging path try_lock mode like shink_page_list so the reclaim context will keep working with next lru pages without being stuck. if it found the rmap lock contended, it rotates the page back to head of lru in both active/inactive lrus to make them consistent behavior, which is basic starting point rather than adding more heristic. Since this patch introduces a new "contended" field as out-param along with try_lock in-param in rmap_walk_control, it's not immutable any longer if the try_lock is set so remove const keywords on rmap related functions. Since rmap walking is already expensive operation, I doubt the const would help sizable benefit( And we didn't have it until 5.17). In a heavy app workload in Android, trace shows following statistics. It almost removes rmap lock contention from reclaim path. Martin Liu reported: Before: max_dur(ms) min_dur(ms) max-min(dur)ms avg_dur(ms) sum_dur(ms) count blocked_function 1632 0 1631 151.542173 31672 209 page_lock_anon_vma_read 601 0 601 145.544681 28817 198 rmap_walk_file After: max_dur(ms) min_dur(ms) max-min(dur)ms avg_dur(ms) sum_dur(ms) count blocked_function NaN NaN NaN NaN NaN 0.0 NaN 0 0 0 0.127645 1 12 rmap_walk_file [minchan@kernel.org: add comment, per Matthew] Link: https://lkml.kernel.org/r/YnNqeB5tUf6LZ57b@google.com Link: https://lkml.kernel.org/r/20220510215423.164547-1-minchan@kernel.orgSigned-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: John Dias <joaodias@google.com> Cc: Tim Murray <timmurray@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Martin Liu <liumartin@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 10 May, 2022 2 commits
-
-
David Hildenbrand authored
Let's mark exclusively mapped anonymous pages with PG_anon_exclusive as exclusive, and use that information to make GUP pins reliable and stay consistent with the page mapped into the page table even if the page table entry gets write-protected. With that information at hand, we can extend our COW logic to always reuse anonymous pages that are exclusive. For anonymous pages that might be shared, the existing logic applies. As already documented, PG_anon_exclusive is usually only expressive in combination with a page table entry. Especially PTE vs. PMD-mapped anonymous pages require more thought, some examples: due to mremap() we can easily have a single compound page PTE-mapped into multiple page tables exclusively in a single process -- multiple page table locks apply. Further, due to MADV_WIPEONFORK we might not necessarily write-protect all PTEs, and only some subpages might be pinned. Long story short: once PTE-mapped, we have to track information about exclusivity per sub-page, but until then, we can just track it for the compound page in the head page and not having to update a whole bunch of subpages all of the time for a simple PMD mapping of a THP. For simplicity, this commit mostly talks about "anonymous pages", while it's for THP actually "the part of an anonymous folio referenced via a page table entry". To not spill PG_anon_exclusive code all over the mm code-base, we let the anon rmap code to handle all PG_anon_exclusive logic it can easily handle. If a writable, present page table entry points at an anonymous (sub)page, that (sub)page must be PG_anon_exclusive. If GUP wants to take a reliably pin (FOLL_PIN) on an anonymous page references via a present page table entry, it must only pin if PG_anon_exclusive is set for the mapped (sub)page. This commit doesn't adjust GUP, so this is only implicitly handled for FOLL_WRITE, follow-up commits will teach GUP to also respect it for FOLL_PIN without FOLL_WRITE, to make all GUP pins of anonymous pages fully reliable. Whenever an anonymous page is to be shared (fork(), KSM), or when temporarily unmapping an anonymous page (swap, migration), the relevant PG_anon_exclusive bit has to be cleared to mark the anonymous page possibly shared. Clearing will fail if there are GUP pins on the page: * For fork(), this means having to copy the page and not being able to share it. fork() protects against concurrent GUP using the PT lock and the src_mm->write_protect_seq. * For KSM, this means sharing will fail. For swap this means, unmapping will fail, For migration this means, migration will fail early. All three cases protect against concurrent GUP using the PT lock and a proper clear/invalidate+flush of the relevant page table entry. This fixes memory corruptions reported for FOLL_PIN | FOLL_WRITE, when a pinned page gets mapped R/O and the successive write fault ends up replacing the page instead of reusing it. It improves the situation for O_DIRECT/vmsplice/... that still use FOLL_GET instead of FOLL_PIN, if fork() is *not* involved, however swapout and fork() are still problematic. Properly using FOLL_PIN instead of FOLL_GET for these GUP users will fix the issue for them. I. Details about basic handling I.1. Fresh anonymous pages page_add_new_anon_rmap() and hugepage_add_new_anon_rmap() will mark the given page exclusive via __page_set_anon_rmap(exclusive=1). As that is the mechanism fresh anonymous pages come into life (besides migration code where we copy the page->mapping), all fresh anonymous pages will start out as exclusive. I.2. COW reuse handling of anonymous pages When a COW handler stumbles over a (sub)page that's marked exclusive, it simply reuses it. Otherwise, the handler tries harder under page lock to detect if the (sub)page is exclusive and can be reused. If exclusive, page_move_anon_rmap() will mark the given (sub)page exclusive. Note that hugetlb code does not yet check for PageAnonExclusive(), as it still uses the old COW logic that is prone to the COW security issue because hugetlb code cannot really tolerate unnecessary/wrong COW as huge pages are a scarce resource. I.3. Migration handling try_to_migrate() has to try marking an exclusive anonymous page shared via page_try_share_anon_rmap(). If it fails because there are GUP pins on the page, unmap fails. migrate_vma_collect_pmd() and __split_huge_pmd_locked() are handled similarly. Writable migration entries implicitly point at shared anonymous pages. For readable migration entries that information is stored via a new "readable-exclusive" migration entry, specific to anonymous pages. When restoring a migration entry in remove_migration_pte(), information about exlusivity is detected via the migration entry type, and RMAP_EXCLUSIVE is set accordingly for page_add_anon_rmap()/hugepage_add_anon_rmap() to restore that information. I.4. Swapout handling try_to_unmap() has to try marking the mapped page possibly shared via page_try_share_anon_rmap(). If it fails because there are GUP pins on the page, unmap fails. For now, information about exclusivity is lost. In the future, we might want to remember that information in the swap entry in some cases, however, it requires more thought, care, and a way to store that information in swap entries. I.5. Swapin handling do_swap_page() will never stumble over exclusive anonymous pages in the swap cache, as try_to_migrate() prohibits that. do_swap_page() always has to detect manually if an anonymous page is exclusive and has to set RMAP_EXCLUSIVE for page_add_anon_rmap() accordingly. I.6. THP handling __split_huge_pmd_locked() has to move the information about exclusivity from the PMD to the PTEs. a) In case we have a readable-exclusive PMD migration entry, simply insert readable-exclusive PTE migration entries. b) In case we have a present PMD entry and we don't want to freeze ("convert to migration entries"), simply forward PG_anon_exclusive to all sub-pages, no need to temporarily clear the bit. c) In case we have a present PMD entry and want to freeze, handle it similar to try_to_migrate(): try marking the page shared first. In case we fail, we ignore the "freeze" instruction and simply split ordinarily. try_to_migrate() will properly fail because the THP is still mapped via PTEs. When splitting a compound anonymous folio (THP), the information about exclusivity is implicitly handled via the migration entries: no need to replicate PG_anon_exclusive manually. I.7. fork() handling fork() handling is relatively easy, because PG_anon_exclusive is only expressive for some page table entry types. a) Present anonymous pages page_try_dup_anon_rmap() will mark the given subpage shared -- which will fail if the page is pinned. If it failed, we have to copy (or PTE-map a PMD to handle it on the PTE level). Note that device exclusive entries are just a pointer at a PageAnon() page. fork() will first convert a device exclusive entry to a present page table and handle it just like present anonymous pages. b) Device private entry Device private entries point at PageAnon() pages that cannot be mapped directly and, therefore, cannot get pinned. page_try_dup_anon_rmap() will mark the given subpage shared, which cannot fail because they cannot get pinned. c) HW poison entries PG_anon_exclusive will remain untouched and is stale -- the page table entry is just a placeholder after all. d) Migration entries Writable and readable-exclusive entries are converted to readable entries: possibly shared. I.8. mprotect() handling mprotect() only has to properly handle the new readable-exclusive migration entry: When write-protecting a migration entry that points at an anonymous page, remember the information about exclusivity via the "readable-exclusive" migration entry type. II. Migration and GUP-fast Whenever replacing a present page table entry that maps an exclusive anonymous page by a migration entry, we have to mark the page possibly shared and synchronize against GUP-fast by a proper clear/invalidate+flush to make the following scenario impossible: 1. try_to_migrate() places a migration entry after checking for GUP pins and marks the page possibly shared. 2. GUP-fast pins the page due to lack of synchronization 3. fork() converts the "writable/readable-exclusive" migration entry into a readable migration entry 4. Migration fails due to the GUP pin (failing to freeze the refcount) 5. Migration entries are restored. PG_anon_exclusive is lost -> We have a pinned page that is not marked exclusive anymore. Note that we move information about exclusivity from the page to the migration entry as it otherwise highly overcomplicates fork() and PTE-mapping a THP. III. Swapout and GUP-fast Whenever replacing a present page table entry that maps an exclusive anonymous page by a swap entry, we have to mark the page possibly shared and synchronize against GUP-fast by a proper clear/invalidate+flush to make the following scenario impossible: 1. try_to_unmap() places a swap entry after checking for GUP pins and clears exclusivity information on the page. 2. GUP-fast pins the page due to lack of synchronization. -> We have a pinned page that is not marked exclusive anymore. If we'd ever store information about exclusivity in the swap entry, similar to migration handling, the same considerations as in II would apply. This is future work. Link: https://lkml.kernel.org/r/20220428083441.37290-13-david@redhat.comSigned-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
David Hildenbrand authored
... and instead convert page_add_anon_rmap() to accept flags. Passing flags instead of bools is usually nicer either way, and we want to more often also pass RMAP_EXCLUSIVE in follow up patches when detecting that an anonymous page is exclusive: for example, when restoring an anonymous page from a writable migration entry. This is a preparation for marking an anonymous page inside page_add_anon_rmap() as exclusive when RMAP_EXCLUSIVE is passed. Link: https://lkml.kernel.org/r/20220428083441.37290-7-david@redhat.comSigned-off-by: David Hildenbrand <david@redhat.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Christoph Hellwig <hch@lst.de> Cc: David Rientjes <rientjes@google.com> Cc: Don Dutile <ddutile@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Jan Kara <jack@suse.cz> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Khalid Aziz <khalid.aziz@oracle.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Liang Zhang <zhangliang5@huawei.com> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.ibm.com> Cc: Nadav Amit <namit@vmware.com> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Pedro Demarchi Gomes <pedrodemargomes@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <guro@fb.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Yang Shi <shy828301@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 29 Apr, 2022 1 commit
-
-
xu xin authored
Some applications or containers want to use KSM by calling madvise() to advise areas of address space to be MERGEABLE. But they may not know which applications are more likely to cause real merges in the deployment. If this patch is applied, it helps them know their corresponding number of merged pages, and then optimize their app code. As current KSM only counts the number of KSM merging pages(e.g. ksm_pages_sharing and ksm_pages_shared) of the whole system, we cannot see the more fine-grained KSM merging, for the upper application optimization, the merging area cannot be set easily according to the KSM page merging probability of each process. Therefore, it is necessary to add extra statistical means so that the upper level users can know the detailed KSM merging information of each process. We add a new proc file named as ksm_merging_pages under /proc/<pid>/ to indicate the involved ksm merging pages of this process. [akpm@linux-foundation.org: fix comment typo, remove BUG_ON()s] Link: https://lkml.kernel.org/r/20220325082318.2352853-1-xu.xin16@zte.com.cnSigned-off-by: xu xin <xu.xin16@zte.com.cn> Reported-by: kernel test robot <lkp@intel.com> Reviewed-by: Yang Yang <yang.yang29@zte.com.cn> Reviewed-by: Ran Xiaokai <ran.xiaokai@zte.com.cn> Reported-by: Zeal Robot <zealci@zte.com.cn> Cc: Kees Cook <keescook@chromium.org> Cc: Alexey Dobriyan <adobriyan@gmail.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Ohhoon Kwon <ohoono.kwon@samsung.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Stephen Brennan <stephen.s.brennan@oracle.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Feng Tang <feng.tang@intel.com> Cc: Yang Yang <yang.yang29@zte.com.cn> Cc: Ran Xiaokai <ran.xiaokai@zte.com.cn> Cc: Zeal Robot <zealci@zte.com.cn> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-
- 22 Mar, 2022 2 commits
-
-
Miaohe Lin authored
Use helper macro __ATTR_RW to define KSM_ATTR to make code more clear. Minor readability improvement. Link: https://lkml.kernel.org/r/20220221115809.26381-1-linmiaohe@huawei.comSigned-off-by: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-
Yang Yang authored
When faults in from swap what used to be a KSM page and that page had been swapped in before, system has to make a copy, and leaves remerging the pages to a later pass of ksmd. That is not good for performace, we'd better to reduce this kind of copy. There are some ways to reduce it, for example lessen swappiness or madvise(, , MADV_MERGEABLE) range. So add this event to support doing this tuning. Just like this patch: "mm, THP, swap: add THP swapping out fallback counting". Link: https://lkml.kernel.org/r/20220113023839.758845-1-yang.yang29@zte.com.cnSigned-off-by: Yang Yang <yang.yang29@zte.com.cn> Reviewed-by: Ran Xiaokai <ran.xiaokai@zte.com.cn> Cc: Hugh Dickins <hughd@google.com> Cc: Yang Shi <yang.shi@linux.alibaba.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Saravanan D <saravanand@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-
- 21 Mar, 2022 1 commit
-
-
Matthew Wilcox (Oracle) authored
The rmap walking functions do not modify the rmap_walk_control, and page_idle_clear_pte_refs() takes advantage of that to move construction of the rmap_walk_control to compile time. This lets us remove an unclean cast. Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
-