- 18 Oct, 2023 40 commits
-
-
Audra Mitchell authored
With the introduction of allocation timestamps being included in page_owner output, each record becomes unique due to the timestamp nanosecond granularity. Remove the check in add_list that tries to collate each record during processing as the memcmp() is just additional overhead at this point. Also keep the allocation timestamps, but allow collation to occur without consideration of the allocation timestamp except in the case were allocation timestamps are requested by the user (the -a option). Link: https://lkml.kernel.org/r/20231013190350.579407-4-audra@redhat.comSigned-off-by:
Audra Mitchell <audra@redhat.com> Acked-by:
Rafael Aquini <aquini@redhat.com> Acked-by:
Vlastimil Babka <vbabka@suse.cz> Cc: Georgi Djakov <djakov@kernel.org> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org>
-
Audra Mitchell authored
With the removal of free timestamps from page_owner output, we no longer need to handle this case or the "unreleased" case. Remove all references to both cases. Link: https://lkml.kernel.org/r/20231013190350.579407-3-audra@redhat.comSigned-off-by:
-
Audra Mitchell authored
Patch series "Fix page_owner's use of free timestamps". While page ower output is used to investigate memory utilization, typically the allocation pathway, the introduction of timestamps to the page owner records caused each record to become unique due to the granularity of the nanosecond timestamp (for example): Page allocated via order 0 ... ts 5206196026 ns, free_ts 5187156703 ns Page allocated via order 0 ... ts 5206198540 ns, free_ts 5187162702 ns Furthermore, the page_owner output only dumps the currently allocated records, so having the free timestamps is nonsensical for the typical use case. In addition, the introduction of timestamps was not properly handled in the page_owner_sort tool causing most use cases to be broken. This series is meant to remove the free timestamps from the page_owner output and fix the page_owner_sort tool so proper collation can occur. This patch (of 5): When printing page_owner data via the sysfs interface, no free pages will ever be dumped due to the series of checks in read_page_owner(): /* * Although we do have the info about past allocation of free * pages, it's not relevant for current memory usage. */ if (!test_bit(PAGE_EXT_OWNER_ALLOCATED, &page_ext->flags)) The free_ts values are still used when dump_page_owner() is called, so keeping the field for other use cases but removing them for the typical page_owner case. Link: https://lkml.kernel.org/r/20231013190350.579407-1-audra@redhat.com Link: https://lkml.kernel.org/r/20231013190350.579407-2-audra@redhat.com Fixes: 866b4852 ("mm/page_owner: record the timestamp of all pages during free") Signed-off-by: -
Lorenzo Stoakes authored
mremap uses vma_merge() in the case where a VMA needs to be extended. This can be significantly simplified and abstracted. This makes it far easier to understand what the actual function is doing, avoids future mistakes in use of the confusing vma_merge() function and importantly allows us to make future changes to how vma_merge() is implemented by knowing explicitly which merge cases each invocation uses. Note that in the mremap() extend case, we perform this merge only when old_len == vma->vm_end - addr. The extension_start, i.e. the start of the extended portion of the VMA is equal to addr + old_len, i.e. vma->vm_end. With this refactoring, vma_merge() is no longer required anywhere except mm/mmap.c, so mark it static. Link: https://lkml.kernel.org/r/f16cbdc2e72d37a1a097c39dc7d1fee8919a1c93.1697043508.git.lstoakes@gmail.comSigned-off-by:
Lorenzo Stoakes <lstoakes@gmail.com> Reviewed-by:
-
Lorenzo Stoakes authored
Only in mmap_region() and copy_vma() do we attempt to merge VMAs which occupy entirely new regions of virtual memory. We can abstract this logic and make the intent of this invocations of it completely explicit, rather than invoking vma_merge() with an inscrutable wall of parameters. This also paves the way for a simplification of the core vma_merge() implementation, as we seek to make it entirely an implementation detail. The VMA merge call in mmap_region() occurs only for file-backed mappings, where each of the parameters previously specified as NULL are defaulted to NULL in vma_init() (called by vm_area_alloc()). This matches the previous behaviour of specifying NULL for a number of fields, however note that prior to this call we pass the VMA to the file system driver via call_mmap(), which may in theory adjust fields that we pass in to vma_merge_new_vma(). Therefore we actually resolve an oversight here by allowing for the fact that the driver may have done this. Link: https://lkml.kernel.org/r/3dc71d17e307756a54781d4a4ce7315cf8b18bea.1697043508.git.lstoakes@gmail.comSigned-off-by:
-
Lorenzo Stoakes authored
Now the common pattern of - attempting a merge via vma_merge() and should this fail splitting VMAs via split_vma() - has been abstracted, the former can be placed into mm/internal.h and the latter made static. In addition, the split_vma() nommu variant also need not be exported. Link: https://lkml.kernel.org/r/405f2be10e20c4e9fbcc9fe6b2dfea105f6642e0.1697043508.git.lstoakes@gmail.comSigned-off-by:
-
Lorenzo Stoakes authored
mprotect() and other functions which change VMA parameters over a range each employ a pattern of:- 1. Attempt to merge the range with adjacent VMAs. 2. If this fails, and the range spans a subset of the VMA, split it accordingly. This is open-coded and duplicated in each case. Also in each case most of the parameters passed to vma_merge() remain the same. Create a new function, vma_modify(), which abstracts this operation, accepting only those parameters which can be changed. To avoid the mess of invoking each function call with unnecessary parameters, create inline wrapper functions for each of the modify operations, parameterised only by what is required to perform the action. We can also significantly simplify the logic - by returning the VMA if we split (or merged VMA if we do not) we no longer need specific handling for merge/split cases in any of the call sites. Note that the userfaultfd_release() case works even though it does not split VMAs - since start is set to vma->vm_start and end is set to vma->vm_end, the split logic does not trigger. In addition, since we calculate pgoff to be equal to vma->vm_pgoff + (start - vma->vm_start) >> PAGE_SHIFT, and start - vma->vm_start will be 0 in this instance, this invocation will remain unchanged. We eliminate a VM_WARN_ON() in mprotect_fixup() as this simply asserts that vma_merge() correctly ensures that flags remain the same, something that is already checked in is_mergeable_vma() and elsewhere, and in any case is not specific to mprotect(). Link: https://lkml.kernel.org/r/0dfa9368f37199a423674bf0ee312e8ea0619044.1697043508.git.lstoakes@gmail.comSigned-off-by:
-
Lorenzo Stoakes authored
Patch series "Abstract vma_merge() and split_vma()", v4. The vma_merge() interface is very confusing and its implementation has led to numerous bugs as a result of that confusion. In addition there is duplication both in invocation of vma_merge(), but also in the common mprotect()-style pattern of attempting a merge, then if this fails, splitting the portion of a VMA about to have its attributes changed. This pattern has been copy/pasted around the kernel in each instance where such an operation has been required, each very slightly modified from the last to make it even harder to decipher what is going on. Simplify the whole thing by dividing the actual uses of vma_merge() and split_vma() into specific and abstracted functions and de-duplicate the vma_merge()/split_vma() pattern altogether. Doing so also opens the door to changing how vma_merge() is implemented - by knowing precisely what cases a caller is invoking rather than having a central interface where anything might happen we can untangle the brittle and confusing vma_merge() implementation into something more workable. For mprotect()-like cases we introduce vma_modify() which performs the vma_merge()/split_vma() pattern, returning a pointer to either the merged or split VMA or an ERR_PTR(err) if the splits fail. We provide a number of inline helper functions to make things even clearer:- * vma_modify_flags() - Prepare to modify the VMA's flags. * vma_modify_flags_name() - Prepare to modify the VMA's flags/anon_vma_name * vma_modify_policy() - Prepare to modify the VMA's mempolicy. * vma_modify_flags_uffd() - Prepare to modify the VMA's flags/uffd context. For cases where a new VMA is attempted to be merged with adjacent VMAs we add:- * vma_merge_new_vma() - Prepare to merge a new VMA. * vma_merge_extend() - Prepare to extend the end of a new VMA. This patch (of 5): The vma_policy() define is a helper specifically for a VMA field so it makes sense to host it in the memory management types header. The anon_vma_name(), anon_vma_name_alloc() and anon_vma_name_free() functions are a little out of place in mm_inline.h as they define external functions, and so it makes sense to locate them in mm_types.h. The purpose of these relocations is to make it possible to abstract static inline wrappers which invoke both of these helpers. Link: https://lkml.kernel.org/r/cover.1697043508.git.lstoakes@gmail.com Link: https://lkml.kernel.org/r/24bfc6c9e382fffbcb0ea8d424392c27d56cc8ca.1697043508.git.lstoakes@gmail.comSigned-off-by:
-
Matthew Wilcox (Oracle) authored
There are no users of wait bookmarks left, so simplify the wait code by removing them. Link: https://lkml.kernel.org/r/20231010035829.544242-2-willy@infradead.orgSigned-off-by:
Matthew Wilcox (Oracle) <willy@infradead.org> Acked-by:
Ingo Molnar <mingo@kernel.org> Cc: Benjamin Segall <bsegall@google.com> Cc: Bin Lai <sclaibin@gmail.com> Cc: Daniel Bristot de Oliveira <bristot@redhat.com> Cc: Dietmar Eggemann <dietmar.eggemann@arm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Juri Lelli <juri.lelli@redhat.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Steven Rostedt (Google) <rostedt@goodmis.org> Cc: Valentin Schneider <vschneid@redhat.com> Cc: Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by:
-
Matthew Wilcox (Oracle) authored
The original problem of the overly long list of waiters on a locked page was solved properly by commit 9a1ea439 ("mm: put_and_wait_on_page_locked() while page is migrated"). In the meantime, using bookmarks for the writeback bit can cause livelocks, so we need to stop using them. Link: https://lkml.kernel.org/r/20231010035829.544242-1-willy@infradead.orgSigned-off-by:
-
Lorenzo Stoakes authored
When mprotect() is used to make unwritable VMAs writable, they have the VM_ACCOUNT flag applied and memory accounted accordingly. If the VMA has had no pages faulted in and is then made unwritable once again, it will remain accounted for, despite not being capable of extending memory usage. Consider:- ptr = mmap(NULL, page_size * 3, PROT_READ, MAP_ANON | MAP_PRIVATE, -1, 0); mprotect(ptr + page_size, page_size, PROT_READ | PROT_WRITE); mprotect(ptr + page_size, page_size, PROT_READ); The first mprotect() splits the range into 3 VMAs and the second fails to merge the three as the middle VMA has VM_ACCOUNT set and the others do not, rendering them unmergeable. This is unnecessary, since no pages have actually been allocated and the middle VMA is not capable of utilising more memory, thereby introducing unnecessary VMA fragmentation (and accounting for more memory than is necessary). Since we cannot efficiently determine which pages map to an anonymous VMA, we have to be very conservative - determining whether any pages at all have been faulted in, by checking whether vma->anon_vma is NULL. We can see that the lack of anon_vma implies that no anonymous pages are present as evidenced by vma_needs_copy() utilising this on fork to determine whether page tables need to be copied. The only place where anon_vma is set NULL explicitly is on fork with VM_WIPEONFORK set, however since this flag is intended to cause the child process to not CoW on a given memory range, it is right to interpret this as indicating the VMA has no faulted-in anonymous memory mapped. If the VMA was forked without VM_WIPEONFORK set, then anon_vma_fork() will have ensured that a new anon_vma is assigned (and correctly related to its parent anon_vma) should any pages be CoW-mapped. The overall operation is safe against races as we hold a write lock against mm->mmap_lock. If we could efficiently look up the VMA's faulted-in pages then we would unaccount all those pages not yet faulted in. However as the original comment alludes this simply isn't currently possible, so we are conservative and account all pages or none at all. Link: https://lkml.kernel.org/r/ad5540371a16623a069f03f4db1739f33cde1fab.1696921767.git.lstoakes@gmail.comSigned-off-by:
Mike Rapoport (IBM) <rppt@kernel.org> Cc: David Hildenbrand <david@redhat.com> Cc: Liam R. Howlett <Liam.Howlett@oracle.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by:
-
Lucy Mielke authored
This fixes a compiler warning when compiling an allyesconfig with W=1: mm/internal.h:1235:9: error: function might be a candidate for `gnu_printf' format attribute [-Werror=suggest-attribute=format] [akpm@linux-foundation.org: fix shrinker_alloc() as welll per Qi Zheng] Link: https://lkml.kernel.org/r/822387b7-4895-4e64-5806-0f56b5d6c447@bytedance.com Link: https://lkml.kernel.org/r/ZSBue-3kM6gI6jCr@mainframe Fixes: c42d50ae ("mm: shrinker: add infrastructure for dynamically allocating shrinker") Signed-off-by:
Lucy Mielke <lucymielke@icloud.com> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Signed-off-by:
-
Zach O'Keefe authored
The 6.0 commits: commit 9fec5168 ("mm: thp: kill transparent_hugepage_active()") commit 7da4e2cb ("mm: thp: kill __transhuge_page_enabled()") merged "can we have THPs in this VMA?" logic that was previously done separately by fault-path, khugepaged, and smaps "THPeligible" checks. During the process, the semantics of the fault path check changed in two ways: 1) A VM_NO_KHUGEPAGED check was introduced (also added to smaps path). 2) We no longer checked if non-anonymous memory had a vm_ops->huge_fault handler that could satisfy the fault. Previously, this check had been done in create_huge_pud() and create_huge_pmd() routines, but after the changes, we never reach those routines. During the review of the above commits, it was determined that in-tree users weren't affected by the change; most notably, since the only relevant user (in terms of THP) of VM_MIXEDMAP or ->huge_fault is DAX, which is explicitly approved early in approval logic. However, this was a bad assumption to make as it assumes the only reason to support ->huge_fault was for DAX (which is not true in general). Remove the VM_NO_KHUGEPAGED check when not in collapse path and give any ->huge_fault handler a chance to handle the fault. Note that we don't validate the file mode or mapping alignment, which is consistent with the behavior before the aforementioned commits. Link: https://lkml.kernel.org/r/20230925200110.1979606-1-zokeefe@google.com Fixes: 7da4e2cb ("mm: thp: kill __transhuge_page_enabled()") Reported-by:
Saurabh Singh Sengar <ssengar@microsoft.com> Signed-off-by:
Zach O'Keefe <zokeefe@google.com> Cc: Yang Shi <shy828301@gmail.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: David Hildenbrand <david@redhat.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Signed-off-by:
-
Nhat Pham authored
This patch add a new kselftest to demonstrate and verify the new hugetlb memcg accounting behavior. Link: https://lkml.kernel.org/r/20231006184629.155543-5-nphamcs@gmail.comSigned-off-by:
Nhat Pham <nphamcs@gmail.com> Cc: Frank van der Linden <fvdl@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Tejun heo <tj@kernel.org> Cc: Yosry Ahmed <yosryahmed@google.com> Cc: Zefan Li <lizefan.x@bytedance.com> Signed-off-by:
-
Nhat Pham authored
Currently, hugetlb memory usage is not acounted for in the memory controller, which could lead to memory overprotection for cgroups with hugetlb-backed memory. This has been observed in our production system. For instance, here is one of our usecases: suppose there are two 32G containers. The machine is booted with hugetlb_cma=6G, and each container may or may not use up to 3 gigantic page, depending on the workload within it. The rest is anon, cache, slab, etc. We can set the hugetlb cgroup limit of each cgroup to 3G to enforce hugetlb fairness. But it is very difficult to configure memory.max to keep overall consumption, including anon, cache, slab etc. fair. What we have had to resort to is to constantly poll hugetlb usage and readjust memory.max. Similar procedure is done to other memory limits (memory.low for e.g). However, this is rather cumbersome and buggy. Furthermore, when there is a delay in memory limits correction, (for e.g when hugetlb usage changes within consecutive runs of the userspace agent), the system could be in an over/underprotected state. This patch rectifies this issue by charging the memcg when the hugetlb folio is utilized, and uncharging when the folio is freed (analogous to the hugetlb controller). Note that we do not charge when the folio is allocated to the hugetlb pool, because at this point it is not owned by any memcg. Some caveats to consider: * This feature is only available on cgroup v2. * There is no hugetlb pool management involved in the memory controller. As stated above, hugetlb folios are only charged towards the memory controller when it is used. Host overcommit management has to consider it when configuring hard limits. * Failure to charge towards the memcg results in SIGBUS. This could happen even if the hugetlb pool still has pages (but the cgroup limit is hit and reclaim attempt fails). * When this feature is enabled, hugetlb pages contribute to memory reclaim protection. low, min limits tuning must take into account hugetlb memory. * Hugetlb pages utilized while this option is not selected will not be tracked by the memory controller (even if cgroup v2 is remounted later on). Link: https://lkml.kernel.org/r/20231006184629.155543-4-nphamcs@gmail.comSigned-off-by:Johannes Weiner <hannes@cmpxchg.org> Cc: Frank van der Linden <fvdl@google.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Rik van Riel <riel@surriel.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeelb@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Tejun heo <tj@kernel.org> Cc: Yosry Ahmed <yosryahmed@google.com> Cc: Zefan Li <lizefan.x@bytedance.com> Signed-off-by:
-
Nhat Pham authored
For most migration use cases, only transfer the memcg data from the old folio to the new folio, and clear the old folio's memcg data. No charging and uncharging will be done. This shaves off some work on the migration path, and avoids the temporary double charging of a folio during its migration. The only exception is replace_page_cache_folio(), which will use the old mem_cgroup_migrate() (now renamed to mem_cgroup_replace_folio). In that context, the isolation of the old page isn't quite as thorough as with migration, so we cannot use our new implementation directly. This patch is the result of the following discussion on the new hugetlb memcg accounting behavior: https://lore.kernel.org/lkml/20231003171329.GB314430@monkey/ Link: https://lkml.kernel.org/r/20231006184629.155543-3-nphamcs@gmail.comSigned-off-by:
-
Nhat Pham authored
Patch series "hugetlb memcg accounting", v4. Currently, hugetlb memory usage is not acounted for in the memory controller, which could lead to memory overprotection for cgroups with hugetlb-backed memory. This has been observed in our production system. For instance, here is one of our usecases: suppose there are two 32G containers. The machine is booted with hugetlb_cma=6G, and each container may or may not use up to 3 gigantic page, depending on the workload within it. The rest is anon, cache, slab, etc. We can set the hugetlb cgroup limit of each cgroup to 3G to enforce hugetlb fairness. But it is very difficult to configure memory.max to keep overall consumption, including anon, cache, slab etcetera fair. What we have had to resort to is to constantly poll hugetlb usage and readjust memory.max. Similar procedure is done to other memory limits (memory.low for e.g). However, this is rather cumbersome and buggy. Furthermore, when there is a delay in memory limits correction, (for e.g when hugetlb usage changes within consecutive runs of the userspace agent), the system could be in an over/underprotected state. This patch series rectifies this issue by charging the memcg when the hugetlb folio is allocated, and uncharging when the folio is freed. In addition, a new selftest is added to demonstrate and verify this new behavior. This patch (of 4): This patch exposes charge committing and cancelling as parts of the memory controller interface. These functionalities are useful when the try_charge() and commit_charge() stages have to be separated by other actions in between (which can fail). One such example is the new hugetlb accounting behavior in the following patch. The patch also adds a helper function to obtain a reference to the current task's memcg. Link: https://lkml.kernel.org/r/20231006184629.155543-1-nphamcs@gmail.com Link: https://lkml.kernel.org/r/20231006184629.155543-2-nphamcs@gmail.comSigned-off-by:
Michal Hocko <mhocko@suse.com> Acked-by:
-
Frank van der Linden authored
Originally, hugetlb_cgroup was the only hugetlb user of tail page structure fields. So, the code defined and checked against HUGETLB_CGROUP_MIN_ORDER to make sure pages weren't too small to use. However, by now, tail page #2 is used to store hugetlb hwpoison and subpool information as well. In other words, without that tail page hugetlb doesn't work. Acknowledge this fact by getting rid of HUGETLB_CGROUP_MIN_ORDER and checks against it. Instead, just check for the minimum viable page order at hstate creation time. Link: https://lkml.kernel.org/r/20231004153248.3842997-1-fvdl@google.comSigned-off-by:
Frank van der Linden <fvdl@google.com> Reviewed-by:
Mike Kravetz <mike.kravetz@oracle.com> Cc: Muchun Song <muchun.song@linux.dev> Signed-off-by:
-
Matthew Wilcox (Oracle) authored
Match how folio_unlock() works by combining the test for PG_waiters with the clearing of PG_writeback. This should have a small performance win, and removes the last user of folio_wake(). Link: https://lkml.kernel.org/r/20231004165317.1061855-18-willy@infradead.orgSigned-off-by:
-
Matthew Wilcox (Oracle) authored
Rather than check the result of test-and-clear, just check that we have the writeback bit set at the start. This wouldn't catch every case, but it's good enough (and enables the next patch). Link: https://lkml.kernel.org/r/20231004165317.1061855-17-willy@infradead.orgSigned-off-by:
-
Matthew Wilcox (Oracle) authored
Optimise folio_end_read() by setting the uptodate bit at the same time we clear the unlock bit. This saves at least one memory barrier and one write-after-write hazard. Link: https://lkml.kernel.org/r/20231004165317.1061855-16-willy@infradead.orgSigned-off-by:
-
Matthew Wilcox (Oracle) authored
Architectures which don't define their own use the one in asm-generic/bitops/lock.h. Get rid of all the ifdefs around "maybe we don't have it". Link: https://lkml.kernel.org/r/20231004165317.1061855-15-willy@infradead.orgSigned-off-by:
Geert Uytterhoeven <geert@linux-m68k.org> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Andreas Dilger <adilger.kernel@dilger.ca> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Christophe Leroy <christophe.leroy@csgroup.eu> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Nicholas Piggin <npiggin@gmail.com> Cc: Palmer Dabbelt <palmer@dabbelt.com> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Richard Henderson <richard.henderson@linaro.org> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by:
-
Matthew Wilcox (Oracle) authored
Inspired by the s390 arch_test_and_clear_bit(), this will surely be more efficient than the generic one defined in filemap.c. Link: https://lkml.kernel.org/r/20231004165317.1061855-14-willy@infradead.orgSigned-off-by:
-
Matthew Wilcox (Oracle) authored
Inspired by the riscv clear_bit_unlock(), this will surely be more efficient than the generic one defined in filemap.c. Link: https://lkml.kernel.org/r/20231004165317.1061855-13-willy@infradead.orgSigned-off-by:
-
Matthew Wilcox (Oracle) authored
Simply remove the ifdef. The assembly is identical to that in the non-optimised case of test_and_clear_bits() on PPC32, and it's not clear to me how the PPC32 optimisation works, nor whether it would work for arch_xor_unlock_is_negative_byte(). If that optimisation would work, someone can implement it later, but this is more efficient than the implementation in filemap.c. Link: https://lkml.kernel.org/r/20231004165317.1061855-12-willy@infradead.orgSigned-off-by:
-
Matthew Wilcox (Oracle) authored
Inspired by the mips test_and_change_bit(), this will surely be more efficient than the generic one defined in filemap.c Link: https://lkml.kernel.org/r/20231004165317.1061855-11-willy@infradead.orgSigned-off-by:
-
Matthew Wilcox (Oracle) authored
Using EOR to clear the guaranteed-to-be-set lock bit will test the negative flag just like the x86 implementation. This should be more efficient than the generic implementation in filemap.c. It would be better if m68k had __GCC_ASM_FLAG_OUTPUTS__. Coldfire doesn't have a byte-sized EOR, so we test bit 7 after the EOR, which is a second memory access, but it's slightly better than the current C code. Link: https://lkml.kernel.org/r/20231004165317.1061855-10-willy@infradead.orgSigned-off-by:
-
Matthew Wilcox (Oracle) authored
Inspired by the alpha clear_bit() and arch_atomic_add_return(), this will surely be more efficient than the generic one defined in filemap.c. Link: https://lkml.kernel.org/r/20231004165317.1061855-9-willy@infradead.orgSigned-off-by:
-
Matthew Wilcox (Oracle) authored
Replace clear_bit_and_unlock_is_negative_byte() with xor_unlock_is_negative_byte(). We have a few places that like to lock a folio, set a flag and unlock it again. Allow for the possibility of combining the latter two operations for efficiency. We are guaranteed that the caller holds the lock, so it is safe to unlock it with the xor. The caller must guarantee that nobody else will set the flag without holding the lock; it is not safe to do this with the PG_dirty flag, for example. Link: https://lkml.kernel.org/r/20231004165317.1061855-8-willy@infradead.orgSigned-off-by:
-
Matthew Wilcox (Oracle) authored
Combine the setting of the uptodate flag with the clearing of the locked flag. Link: https://lkml.kernel.org/r/20231004165317.1061855-7-willy@infradead.orgSigned-off-by:
-
Matthew Wilcox (Oracle) authored
There are two places that we can use this new helper. Link: https://lkml.kernel.org/r/20231004165317.1061855-6-willy@infradead.orgSigned-off-by:
-
Matthew Wilcox (Oracle) authored
folio_end_read() is the perfect fit for ext4. Link: https://lkml.kernel.org/r/20231004165317.1061855-5-willy@infradead.orgSigned-off-by:
-
Matthew Wilcox (Oracle) authored
Provide a function for filesystems to call when they have finished reading an entire folio. Link: https://lkml.kernel.org/r/20231004165317.1061855-4-willy@infradead.orgSigned-off-by:
-
Matthew Wilcox (Oracle) authored
Perform one atomic operation (acquiring the spinlock) instead of two (spinlock & atomic_sub) per read completion. Link: https://lkml.kernel.org/r/20231004165317.1061855-3-willy@infradead.orgSigned-off-by:
-
Matthew Wilcox (Oracle) authored
Patch series "Add folio_end_read", v2. The core of this patchset is the new folio_end_read() call which filesystems can use when finishing a page cache read instead of separate calls to mark the folio uptodate and unlock it. As an illustration of its use, I converted ext4, iomap & mpage; more can be converted. I think that's useful by itself, but the interesting optimisation is that we can implement that with a single XOR instruction that sets the uptodate bit, clears the lock bit, tests the waiter bit and provides a write memory barrier. That removes one memory barrier and one atomic instruction from each page read, which seems worth doing. That's in patch 15. The last two patches could be a separate series, but basically we can do the same thing with the writeback flag that we do with the unlock flag; clear it and test the waiters bit at the same time. This patch (of 17): This is really preparation for the next patch, but it lets us call folio_mark_uptodate() in just one place instead of two. Link: https://lkml.kernel.org/r/20231004165317.1061855-1-willy@infradead.org Link: https://lkml.kernel.org/r/20231004165317.1061855-2-willy@infradead.orgSigned-off-by:
-
Breno Leitao authored
Create a selftest that exercises the race between page faults and madvise(MADV_DONTNEED) in the same huge page. Do it by running two threads that touches the huge page and madvise(MADV_DONTNEED) at the same time. In case of a SIGBUS coming at pagefault, the test should fail, since we hit the bug. The test doesn't have a signal handler, and if it fails, it fails like the following ---------------------------------- running ./hugetlb_fault_after_madv ---------------------------------- ./run_vmtests.sh: line 186: 595563 Bus error (core dumped) "$@" [FAIL] This selftest goes together with the fix of the bug[1] itself. [1] https://lore.kernel.org/all/20231001005659.2185316-1-riel@surriel.com/#r Link: https://lkml.kernel.org/r/20231005163922.87568-3-leitao@debian.orgSigned-off-by:
Breno Leitao <leitao@debian.org> Reviewed-by:
Rik van Riel <riel@surriel.com> Tested-by:
-
Breno Leitao authored
Patch series "New selftest for mm", v2. This is a simple test case that reproduces an mm problem[1], where a page fault races with madvise(), and it is not trivial to reproduce and debug. This test-case aims to avoid such race problems from happening again, impacting workloads that leverages external allocators, such as tcmalloc, jemalloc, etc. [1] https://lore.kernel.org/all/20231001005659.2185316-1-riel@surriel.com/#r This patch (of 2): get_free_hugepages() is helpful for other hugepage tests. Export it to the common file (vm_util.c) to be reused. Link: https://lkml.kernel.org/r/20231005163922.87568-1-leitao@debian.org Link: https://lkml.kernel.org/r/20231005163922.87568-2-leitao@debian.orgSigned-off-by:
-
Mark-PK Tsai authored
Some architectures have implemented optimized copy_page for full page copying, such as arm. On my arm platform, use the copy_page helper for single page copying is about 10 percent faster than memcpy. Link: https://lkml.kernel.org/r/20231006060245.7411-1-mark-pk.tsai@mediatek.comSigned-off-by:
Mark-PK Tsai <mark-pk.tsai@mediatek.com> Reviewed-by:
Sergey Senozhatsky <senozhatsky@chromium.org> Cc: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> Cc: Matthias Brugger <matthias.bgg@gmail.com> Cc: Minchan Kim <minchan@kernel.org> Cc: YJ Chiang <yj.chiang@mediatek.com> Signed-off-by:
-
Pankaj Raghav authored
filemap_get_folios() is filemap_get_folios_tag() with XA_PRESENT as the tag that is being matched. Return filemap_get_folios_tag() with XA_PRESENT as the tag instead of duplicating the code in filemap_get_folios(). No functional changes. Link: https://lkml.kernel.org/r/20231006110120.136809-1-kernel@pankajraghav.comSigned-off-by:
Pankaj Raghav <p.raghav@samsung.com> Reviewed-by:
-
Kemeng Shi authored
The next_page is only used to forward page in case target is in second half range. Move forward page directly to remove unnecessary next_page. Link: https://lkml.kernel.org/r/20230927103514.98281-3-shikemeng@huaweicloud.comSigned-off-by:
Kemeng Shi <shikemeng@huaweicloud.com> Acked-by:
Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by:
-
