- 29 Apr, 2022 40 commits
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Miaohe Lin authored
It's not guaranteed that highest will be above the min_pfn. If highest is below the min_pfn, migrate_pfn and free_pfn can meet prematurely and lead to some useless work. Make sure highest is above min_pfn to avoid making a futile effort. Link: https://lkml.kernel.org/r/20220418141253.24298-13-linmiaohe@huawei.comSigned-off-by:
Miaohe Lin <linmiaohe@huawei.com> Cc: Charan Teja Kalla <charante@codeaurora.org> Cc: David Hildenbrand <david@redhat.com> Cc: Pintu Kumar <pintu@codeaurora.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org>
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Miaohe Lin authored
Since commit efe771c7 ("mm, compaction: always finish scanning of a full pageblock"), compaction will always finish scanning a pageblock. And migrate_pfn is assured to align with pageblock_nr_pages when we reach here. So we will always return COMPACT_SUCCESS if a suitable fallback is found due to the below IS_ALIGNED check of migrate_pfn. Simplify the code to make this clear and improve the readability. No functional change intended. Link: https://lkml.kernel.org/r/20220418141253.24298-12-linmiaohe@huawei.comSigned-off-by:
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Miaohe Lin authored
When compact_result indicates that the allocation should now succeed, i.e. compact_result = COMPACT_SUCCESS, compaction_zonelist_suitable should return false because there is no need to do compaction now. Link: https://lkml.kernel.org/r/20220418141253.24298-11-linmiaohe@huawei.comSigned-off-by:
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Miaohe Lin authored
It's possible that kcompactd_run could fail to run kcompactd for a hot added node and leave pgdat->kcompactd as NULL. So pgdat->kcompactd should be checked here to avoid possible NULL pointer dereference. Link: https://lkml.kernel.org/r/20220418141253.24298-10-linmiaohe@huawei.comSigned-off-by:
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Miaohe Lin authored
Since commit 282722b0 ("mm, compaction: restrict async compaction to pageblocks of same migratetype"), async direct compaction is restricted to scan the pageblocks of same migratetype. Correct the comment accordingly. Link: https://lkml.kernel.org/r/20220418141253.24298-9-linmiaohe@huawei.comSigned-off-by:
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Miaohe Lin authored
Use helper compound_nr to make use of compound_nr when CONFIG_64BIT and simplify the code a bit. Link: https://lkml.kernel.org/r/20220418141253.24298-8-linmiaohe@huawei.comSigned-off-by:
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Miaohe Lin authored
Always use COMPACT_CLUSTER_MAX here as we're doing the compaction. Minor improvements in readability. Link: https://lkml.kernel.org/r/20220418141253.24298-7-linmiaohe@huawei.comSigned-off-by:
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Miaohe Lin authored
checked_pageblock is already removed and suitable_migration_target is not rechecked under the zone lock since commit f8224aa5 ("mm, compaction: do not recheck suitable_migration_target under lock"). Correct the comment accordingly. Link: https://lkml.kernel.org/r/20220418141253.24298-6-linmiaohe@huawei.comSigned-off-by:
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Miaohe Lin authored
Since commit cf66f070 ("mm, compaction: do not consider a need to reschedule as contention"), async compaction won't abort when scheduling is needed. Correct the relevant comment accordingly. Link: https://lkml.kernel.org/r/20220418141253.24298-5-linmiaohe@huawei.comSigned-off-by:
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Miaohe Lin authored
isolate_start_pfn is unused when cc->nr_freepages ! = 0. Otherwise cc->free_pfn will overwrite it unconditionally. So we should remove this unneeded and somewhat misleading assignment. Link: https://lkml.kernel.org/r/20220418141253.24298-4-linmiaohe@huawei.comSigned-off-by:
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Miaohe Lin authored
pfn is unused in this do while loop. Remove the unneeded pfn update. Link: https://lkml.kernel.org/r/20220418141253.24298-3-linmiaohe@huawei.comSigned-off-by:
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Miaohe Lin authored
Patch series "A few cleanup and fixup patches for compaction". This series contains a few patches to clean up some obsolete comment, remove unneeded return value and so on. Also we fix the possible NULL pointer dereference. More details can be found in the respective changelogs. This patch (of 12): The return value of kcompactd_run() is unused now. Clean it up. Link: https://lkml.kernel.org/r/20220418141253.24298-1-linmiaohe@huawei.com Link: https://lkml.kernel.org/r/20220418141253.24298-2-linmiaohe@huawei.comSigned-off-by:
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Yang Yang authored
Users may use ksm by calling madvise(, , MADV_MERGEABLE) when they want to save memory, it's a tradeoff by suffering delay on ksm cow. Users can get to know how much memory ksm saved by reading /sys/kernel/mm/ksm/pages_sharing, but they don't know what's the costs of ksm cow, and this is important of some delay sensitive tasks. So add ksm cow events to help users evaluate whether or how to use ksm. Also update Documentation/admin-guide/mm/ksm.rst with new added events. Link: https://lkml.kernel.org/r/20220331035616.2390805-1-yang.yang29@zte.com.cnSigned-off-by:
Yang Yang <yang.yang29@zte.com.cn> Reviewed-by:
David Hildenbrand <david@redhat.com> Reviewed-by:
xu xin <xu.xin16@zte.com.cn> Reviewed-by:
Ran Xiaokai <ran.xiaokai@zte.com.cn> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Saravanan D <saravanand@fb.com> Cc: Minchan Kim <minchan@kernel.org> Cc: John Hubbard <jhubbard@nvidia.com> Signed-off-by:
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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:
kernel test robot <lkp@intel.com> Reviewed-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:
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Peter Xu authored
The stub for non_swap_entry() may not help much, because MAX_SWAPFILES has already contained all the information to decide whether a swap entry is real swap entry or pesudo ones (migrations, ...). There can be some performance influences on non_swap_entry() with below conditions all met: !CONFIG_MIGRATION && !CONFIG_MEMORY_FAILURE && !CONFIG_DEVICE_PRIVATE But that's definitely not the major config most machines will use, at the meantime it's already in a slow path of swap entry (being parsed from a swap pte), so IMHO it shouldn't be a major issue. Also according to the analysis from Alistair, somehow the stub didn't do the job right [1]. To make the code cleaner, let's drop the stub. [1] https://lore.kernel.org/lkml/8735ihbw6g.fsf@nvdebian.thelocal/ Note: the uffd-wp shmem & hugetlbfs series will need this patch to make sure swap entries work as expected with below config as spotted by Alistair: !CONFIG_MIGRATION && !CONFIG_MEMORY_FAILURE && !CONFIG_DEVICE_PRIVATE && CONFIG_PTE_MARKER (PS: this config should mostly never gonna happen, though, afaict..) Link: https://lkml.kernel.org/r/20220413191147.66645-1-peterx@redhat.comSigned-off-by:
Peter Xu <peterx@redhat.com> Reviewed-by:
Alistair Popple <apopple@nvidia.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by:
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Joao Martins authored
Currently memmap_init_zone_device() ends up initializing 32768 pages when it only needs to initialize 128 given tail page reuse. That number is worse with 1GB compound pages, 262144 instead of 128. Update memmap_init_zone_device() to skip redundant initialization, detailed below. When a pgmap @vmemmap_shift is set, all pages are mapped at a given huge page alignment and use compound pages to describe them as opposed to a struct per 4K. With @vmemmap_shift > 0 and when struct pages are stored in ram (!altmap) most tail pages are reused. Consequently, the amount of unique struct pages is a lot smaller than the total amount of struct pages being mapped. The altmap path is left alone since it does not support memory savings based on compound pages devmap. Link: https://lkml.kernel.org/r/20220420155310.9712-6-joao.m.martins@oracle.comSigned-off-by:
Joao Martins <joao.m.martins@oracle.com> Reviewed-by:
Muchun Song <songmuchun@bytedance.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Jane Chu <jane.chu@oracle.com> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Vishal Verma <vishal.l.verma@intel.com> Signed-off-by:
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Joao Martins authored
A compound devmap is a dev_pagemap with @vmemmap_shift > 0 and it means that pages are mapped at a given huge page alignment and utilize uses compound pages as opposed to order-0 pages. Take advantage of the fact that most tail pages look the same (except the first two) to minimize struct page overhead. Allocate a separate page for the vmemmap area which contains the head page and separate for the next 64 pages. The rest of the subsections then reuse this tail vmemmap page to initialize the rest of the tail pages. Sections are arch-dependent (e.g. on x86 it's 64M, 128M or 512M) and when initializing compound devmap with big enough @vmemmap_shift (e.g. 1G PUD) it may cross multiple sections. The vmemmap code needs to consult @pgmap so that multiple sections that all map the same tail data can refer back to the first copy of that data for a given gigantic page. On compound devmaps with 2M align, this mechanism lets 6 pages be saved out of the 8 necessary PFNs necessary to set the subsection's 512 struct pages being mapped. On a 1G compound devmap it saves 4094 pages. Altmap isn't supported yet, given various restrictions in altmap pfn allocator, thus fallback to the already in use vmemmap_populate(). It is worth noting that altmap for devmap mappings was there to relieve the pressure of inordinate amounts of memmap space to map terabytes of pmem. With compound pages the motivation for altmaps for pmem gets reduced. Link: https://lkml.kernel.org/r/20220420155310.9712-5-joao.m.martins@oracle.comSigned-off-by:
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Joao Martins authored
In preparation for device-dax for using hugetlbfs compound page tail deduplication technique, move the comment block explanation into a common place in Documentation/vm. Link: https://lkml.kernel.org/r/20220420155310.9712-4-joao.m.martins@oracle.comSigned-off-by:
Dan Williams <dan.j.williams@intel.com> Suggested-by:
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Joao Martins authored
In preparation for describing a memmap with compound pages, move the actual pte population logic into a separate function vmemmap_populate_address() and have a new helper vmemmap_populate_range() walk through all base pages it needs to populate. While doing that, change the helper to use a pte_t* as return value, rather than an hardcoded errno of 0 or -ENOMEM. Link: https://lkml.kernel.org/r/20220420155310.9712-3-joao.m.martins@oracle.comSigned-off-by:
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Joao Martins authored
Patch series "sparse-vmemmap: memory savings for compound devmaps (device-dax)", v9. This series minimizes 'struct page' overhead by pursuing a similar approach as Muchun Song series "Free some vmemmap pages of hugetlb page" (now merged since v5.14), but applied to devmap with @vmemmap_shift (device-dax). The vmemmap dedpulication original idea (already used in HugeTLB) is to reuse/deduplicate tail page vmemmap areas, particular the area which only describes tail pages. So a vmemmap page describes 64 struct pages, and the first page for a given ZONE_DEVICE vmemmap would contain the head page and 63 tail pages. The second vmemmap page would contain only tail pages, and that's what gets reused across the rest of the subsection/section. The bigger the page size, the bigger the savings (2M hpage -> save 6 vmemmap pages; 1G hpage -> save 4094 vmemmap pages). This is done for PMEM /specifically only/ on device-dax configured namespaces, not fsdax. In other words, a devmap with a @vmemmap_shift. In terms of savings, per 1Tb of memory, the struct page cost would go down with compound devmap: * with 2M pages we lose 4G instead of 16G (0.39% instead of 1.5% of total memory) * with 1G pages we lose 40MB instead of 16G (0.0014% instead of 1.5% of total memory) The series is mostly summed up by patch 4, and to summarize what the series does: Patches 1 - 3: Minor cleanups in preparation for patch 4. Move the very nice docs of hugetlb_vmemmap.c into a Documentation/vm/ entry. Patch 4: Patch 4 is the one that takes care of the struct page savings (also referred to here as tail-page/vmemmap deduplication). Much like Muchun series, we reuse the second PTE tail page vmemmap areas across a given @vmemmap_shift On important difference though, is that contrary to the hugetlbfs series, there's no vmemmap for the area because we are late-populating it as opposed to remapping a system-ram range. IOW no freeing of pages of already initialized vmemmap like the case for hugetlbfs, which greatly simplifies the logic (besides not being arch-specific). altmap case unchanged and still goes via the vmemmap_populate(). Also adjust the newly added docs to the device-dax case. [Note that device-dax is still a little behind HugeTLB in terms of savings. I have an additional simple patch that reuses the head vmemmap page too, as a follow-up. That will double the savings and namespaces initialization.] Patch 5: Initialize fewer struct pages depending on the page size with DRAM backed struct pages -- because fewer pages are unique and most tail pages (with bigger vmemmap_shift). NVDIMM namespace bootstrap improves from ~268-358 ms to ~80-110/<1ms on 128G NVDIMMs with 2M and 1G respectivally. And struct page needed capacity will be 3.8x / 1071x smaller for 2M and 1G respectivelly. Tested on x86 with 1.5Tb of pmem (including pinning, and RDMA registration/deregistration scalability with 2M MRs) This patch (of 5): In support of using compound pages for devmap mappings, plumb the pgmap down to the vmemmap_populate implementation. Note that while altmap is retrievable from pgmap the memory hotplug code passes altmap without pgmap[*], so both need to be independently plumbed. So in addition to @altmap, pass @pgmap to sparse section populate functions namely: sparse_add_section section_activate populate_section_memmap __populate_section_memmap Passing @pgmap allows __populate_section_memmap() to both fetch the vmemmap_shift in which memmap metadata is created for and also to let sparse-vmemmap fetch pgmap ranges to co-relate to a given section and pick whether to just reuse tail pages from past onlined sections. While at it, fix the kdoc for @altmap for sparse_add_section(). [*] https://lore.kernel.org/linux-mm/20210319092635.6214-1-osalvador@suse.de/ Link: https://lkml.kernel.org/r/20220420155310.9712-1-joao.m.martins@oracle.com Link: https://lkml.kernel.org/r/20220420155310.9712-2-joao.m.martins@oracle.comSigned-off-by: -
Muchun Song authored
The word of "free" is not expressive enough to express the feature of optimizing vmemmap pages associated with each HugeTLB, rename this keywork to "optimize". In this patch , cheanup configs to make code more expressive. Link: https://lkml.kernel.org/r/20220404074652.68024-4-songmuchun@bytedance.comSigned-off-by:
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Muchun Song authored
The word of "free" is not expressive enough to express the feature of optimizing vmemmap pages associated with each HugeTLB, rename this keywork to "optimize". In this patch , cheanup the static key and hugetlb_free_vmemmap_enabled() to make code more expressive. Link: https://lkml.kernel.org/r/20220404074652.68024-3-songmuchun@bytedance.comSigned-off-by:
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Muchun Song authored
Patch series "cleanup hugetlb_vmemmap". The word of "free" is not expressive enough to express the feature of optimizing vmemmap pages associated with each HugeTLB, rename this keywork to "optimize" is more clear. In this series, cheanup related codes to make it more clear and expressive. This is suggested by David. This patch (of 3): The word of "free" is not expressive enough to express the feature of optimizing vmemmap pages associated with each HugeTLB, rename this keywork to "optimize". And some function names are prefixed with "huge_page" instead of "hugetlb", it is easily to be confused with THP. In this patch, cheanup related functions to make code more clear and expressive. Link: https://lkml.kernel.org/r/20220404074652.68024-1-songmuchun@bytedance.com Link: https://lkml.kernel.org/r/20220404074652.68024-2-songmuchun@bytedance.comSigned-off-by:
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Ma Wupeng authored
Previous 0x100000 is used to check the 4G limit in find_zone_movable_pfns_for_nodes(). This is right in x86 because the page size can only be 4K. But 16K and 64K are available in arm64. So replace it with PHYS_PFN(SZ_4G). Link: https://lkml.kernel.org/r/20220414101314.1250667-8-mawupeng1@huawei.comSigned-off-by:
Ma Wupeng <mawupeng1@huawei.com> Reviewed-by:
Anshuman Khandual <anshuman.khandual@arm.com> Acked-by:
Ard Biesheuvel <ardb@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Signed-off-by:
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Miaohe Lin authored
When old_len == new_len, do_munmap will return -EINVAL due to len == 0. This errno will be simply ignored because of old_len != new_len check. So it is unnecessary to call do_munmap when old_len == new_len because nothing is actually done. Link: https://lkml.kernel.org/r/20220401081023.37080-1-linmiaohe@huawei.comSigned-off-by:
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Miaohe Lin authored
Use helper mlock_future_check() to check whether it's safe to resize the locked_vm to simplify the code. Minor readability improvement. Link: https://lkml.kernel.org/r/20220322112004.27380-1-linmiaohe@huawei.comSigned-off-by:
Wei Yang <richard.weiyang@gmail.com> Signed-off-by:
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Anshuman Khandual authored
There are no platforms left which use arch_vm_get_page_prot(). Just drop generic arch_vm_get_page_prot(). Link: https://lkml.kernel.org/r/20220414062125.609297-8-anshuman.khandual@arm.com Cc: Andrew Morton <akpm@linux-foundation.org> Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org Reviewed-by:
Christophe Leroy <christophe.leroy@csgroup.eu> Reviewed-by:
Catalin Marinas <catalin.marinas@arm.com> Signed-off-by:
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Anshuman Khandual authored
There are no platforms left which subscribe ARCH_HAS_FILTER_PGPROT. Hence drop generic arch_filter_pgprot() and also config ARCH_HAS_FILTER_PGPROT. Link: https://lkml.kernel.org/r/20220414062125.609297-7-anshuman.khandual@arm.comSigned-off-by:
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Christoph Hellwig authored
This defines and exports a platform specific custom vm_get_page_prot() via subscribing ARCH_HAS_VM_GET_PAGE_PROT. This also unsubscribes from config ARCH_HAS_FILTER_PGPROT, after dropping off arch_filter_pgprot() and arch_vm_get_page_prot(). Link: https://lkml.kernel.org/r/20220414062125.609297-6-anshuman.khandual@arm.comSigned-off-by:
Christoph Hellwig <hch@infradead.org> Signed-off-by:
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Anshuman Khandual authored
This defines and exports a platform specific custom vm_get_page_prot() via subscribing ARCH_HAS_VM_GET_PAGE_PROT. It localizes arch_vm_get_page_prot() as sparc_vm_get_page_prot() and moves near vm_get_page_prot(). Link: https://lkml.kernel.org/r/20220414062125.609297-5-anshuman.khandual@arm.comSigned-off-by:
David S. Miller <davem@davemloft.net> Reviewed-by:
Khalid Aziz <khalid.aziz@oracle.com> Reviewed-by:
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Anshuman Khandual authored
This defines and exports a platform specific custom vm_get_page_prot() via subscribing ARCH_HAS_VM_GET_PAGE_PROT. It localizes arch_vm_get_page_prot() and moves it near vm_get_page_prot(). Link: https://lkml.kernel.org/r/20220414062125.609297-4-anshuman.khandual@arm.comSigned-off-by:
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Anshuman Khandual authored
This defines and exports a platform specific custom vm_get_page_prot() via subscribing ARCH_HAS_VM_GET_PAGE_PROT. While here, this also localizes arch_vm_get_page_prot() as __vm_get_page_prot() and moves it near vm_get_page_prot(). Link: https://lkml.kernel.org/r/20220414062125.609297-3-anshuman.khandual@arm.comSigned-off-by:
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Anshuman Khandual authored
Patch series "mm/mmap: Drop arch_vm_get_page_prot() and arch_filter_pgprot()", v7. protection_map[] is an array based construct that translates given vm_flags combination. This array contains page protection map, which is populated by the platform via [__S000 .. __S111] and [__P000 .. __P111] exported macros. Primary usage for protection_map[] is for vm_get_page_prot(), which is used to determine page protection value for a given vm_flags. vm_get_page_prot() implementation, could again call platform overrides arch_vm_get_page_prot() and arch_filter_pgprot(). Some platforms override protection_map[] that was originally built with __SXXX/__PXXX with different runtime values. Currently there are multiple layers of abstraction i.e __SXXX/__PXXX macros , protection_map[], arch_vm_get_page_prot() and arch_filter_pgprot() built between the platform and generic MM, finally defining vm_get_page_prot(). Hence this series proposes to drop later two abstraction levels and instead just move the responsibility of defining vm_get_page_prot() to the platform (still utilizing generic protection_map[] array) itself making it clean and simple. This first introduces ARCH_HAS_VM_GET_PAGE_PROT which enables the platforms to define custom vm_get_page_prot(). This starts converting platforms that define the overrides arch_filter_pgprot() or arch_vm_get_page_prot() which enables for those constructs to be dropped off completely. The series has been inspired from an earlier discuss with Christoph Hellwig https://lore.kernel.org/all/1632712920-8171-1-git-send-email-anshuman.khandual@arm.com/ This patch (of 7): Add a new config ARCH_HAS_VM_GET_PAGE_PROT, which when subscribed enables a given platform to define its own vm_get_page_prot() but still utilizing the generic protection_map[] array. Link: https://lkml.kernel.org/r/20220414062125.609297-1-anshuman.khandual@arm.com Link: https://lkml.kernel.org/r/20220414062125.609297-2-anshuman.khandual@arm.comSigned-off-by:
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Miaohe Lin authored
Use helper mlock_future_check() to check whether it's safe to enlarge the locked_vm to simplify the code. Minor readability improvement. Link: https://lkml.kernel.org/r/20220402032231.64974-1-linmiaohe@huawei.comSigned-off-by:
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Anshuman Khandual authored
protection_map[] maps vm_flags access combinations into page protection value as defined by the platform via __PXXX and __SXXX macros. The array indices in protection_map[], represents vm_flags access combinations but it's not very intuitive to derive. This makes it clear and explicit. Link: https://lkml.kernel.org/r/20220404031840.588321-3-anshuman.khandual@arm.comSigned-off-by:
Christoph Hellwig <hch@lst.de> Signed-off-by:
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Anshuman Khandual authored
Patch series "mm: protection_map[] cleanups". This patch (of 2): Although protection_map[] contains the platform defined page protection map for a given vm_flags combination, vm_get_page_prot() is the right interface to use. This will also reduce dependency on protection_map[] which is going to be dropped off completely later on. Link: https://lkml.kernel.org/r/20220404031840.588321-1-anshuman.khandual@arm.com Link: https://lkml.kernel.org/r/20220404031840.588321-2-anshuman.khandual@arm.comSigned-off-by:
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Jianxing Wang authored
free a large list of pages maybe cause rcu_sched starved on non-preemptible kernels. howerver free_unref_page_list maybe can't cond_resched as it maybe called in interrupt or atomic context, especially can't detect atomic context in CONFIG_PREEMPTION=n. The issue is detected in guest with kvm cpu 200% overcommit, however I didn't see the warning in the host with the same application. I'm sure that the patch is needed for guest kernel, but no sure for host. To reproduce, set up two virtual machines in one host machine, per vm has the same number cpu and half memory of host. the run ltpstress.sh in per vm, then will see rcu stall warning.kernel is preempt disabled, append kernel command 'preempt=none' if enable dynamic preempt . It could detected in loongson machine(32 core, 128G mem) and ProLiant DL380 Gen9(x86 E5-2680, 28 core, 64G mem) tlb flush batch count depends on PAGE_SIZE, it's too large if PAGE_SIZE > 4K, here limit free batch count with 512. And add schedule point in tlb_batch_pages_flush. rcu: rcu_sched kthread starved for 5359 jiffies! g454793 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=19 [...] Call Trace: free_unref_page_list+0x19c/0x270 release_pages+0x3cc/0x498 tlb_flush_mmu_free+0x44/0x70 zap_pte_range+0x450/0x738 unmap_page_range+0x108/0x240 unmap_vmas+0x74/0xf0 unmap_region+0xb0/0x120 do_munmap+0x264/0x438 vm_munmap+0x58/0xa0 sys_munmap+0x10/0x20 syscall_common+0x24/0x38 Link: https://lkml.kernel.org/r/20220317072857.2635262-1-wangjianxing@loongson.cnSigned-off-by:
Jianxing Wang <wangjianxing@loongson.cn> Signed-off-by:
Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will@kernel.org> Cc: Nicholas Piggin <npiggin@gmail.com> Signed-off-by:
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Rolf Eike Beer authored
In case the lock is actually not held at this point. Link: https://lkml.kernel.org/r/5827758.TJ1SttVevJ@mobilepool36.emlix.comSigned-off-by:
Rolf Eike Beer <eb@emlix.com> Reviewed-by:
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Axel Rasmussen authored
These might not be issues yet, but they make the script more fragile. Also by fixing them we give a better example to future readers, who might copy/paste or otherwise re-use snippets from our script. - Use "read -r", since we don't ever want read to be interpreting '\' characters as escape sequences... - Quote variables, to deal with spaces properly. - Use $() instead of the older and harder-to-nest ``. - Get rid of superfluous "$" prefixes inside arithmetic $(()). Link: https://lkml.kernel.org/r/20220421224928.1848230-2-axelrasmussen@google.comSigned-off-by:
Axel Rasmussen <axelrasmussen@google.com> Cc: Shuah Khan <shuah@kernel.org> Signed-off-by:
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Axel Rasmussen authored
Previously, each test printed out its own header, dealt with its own return code, etc. By just putting this standard stuff in a function, we can delete > 300 lines from the script. This also makes adding future tests easier. And, it gets rid of various inconsistencies that already exist: - Some tests correctly deal with ksft_skip, but others don't. - Some tests just print the executable name, others print arguments, and yet others print some comment in the header. - Most tests print out a header with two separator lines, but not the HMM smoke test or the memfd_secret test, which only print one. - We had a redundant "exit" at the end, with all the boilerplate it's an easy oversight. Link: https://lkml.kernel.org/r/20220421224928.1848230-1-axelrasmussen@google.comSigned-off-by:
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