pm24.git/mm/debug.c, branch v6.2-rc3

mm,thp,rmap: simplify compound page mapcount handling

2022-11-30T23:58:46Z

Compound page (folio) mapcount calculations have been different for anon and file (or shmem) THPs, and involved the obscure PageDoubleMap flag. And each huge mapping and unmapping of a file (or shmem) THP involved atomically incrementing and decrementing the mapcount of every subpage of that huge page, dirtying many struct page cachelines. Add subpages_mapcount field to the struct folio and first tail page, so that the total of subpage mapcounts is available in one place near the head: then page_mapcount() and total_mapcount() and page_mapped(), and their folio equivalents, are so quick that anon and file and hugetlb don't need to be optimized differently. Delete the unloved PageDoubleMap. page_add and page_remove rmap functions must now maintain the subpages_mapcount as well as the subpage _mapcount, when dealing with pte mappings of huge pages; and correct maintenance of NR_ANON_MAPPED and NR_FILE_MAPPED statistics still needs reading through the subpages, using nr_subpages_unmapped() - but only when first or last pmd mapping finds subpages_mapcount raised (double-map case, not the common case). But are those counts (used to decide when to split an anon THP, and in vmscan's pagecache_reclaimable heuristic) correctly maintained? Not quite: since page_remove_rmap() (and also split_huge_pmd()) is often called without page lock, there can be races when a subpage pte mapcount 0<->1 while compound pmd mapcount 0<->1 is scanning - races which the previous implementation had prevented. The statistics might become inaccurate, and even drift down until they underflow through 0. That is not good enough, but is better dealt with in a followup patch. Update a few comments on first and second tail page overlaid fields. hugepage_add_new_anon_rmap() has to "increment" compound_mapcount, but subpages_mapcount and compound_pincount are already correctly at 0, so delete its reinitialization of compound_pincount. A simple 100 X munmap(mmap(2GB, MAP_SHARED|MAP_POPULATE, tmpfs), 2GB) took 18 seconds on small pages, and used to take 1 second on huge pages, but now takes 119 milliseconds on huge pages. Mapping by pmds a second time used to take 860ms and now takes 92ms; mapping by pmds after mapping by ptes (when the scan is needed) used to take 870ms and now takes 495ms. But there might be some benchmarks which would show a slowdown, because tail struct pages now fall out of cache until final freeing checks them. Link: https://lkml.kernel.org/r/47ad693-717-79c8-e1ba-46c3a6602e48@google.com Signed-off-by: Hugh Dickins Acked-by: Kirill A. Shutemov Cc: David Hildenbrand Cc: James Houghton Cc: John Hubbard Cc: Matthew Wilcox (Oracle) Cc: Miaohe Lin Cc: Mike Kravetz Cc: Mina Almasry Cc: Muchun Song Cc: Naoya Horiguchi Cc: Peter Xu Cc: Sidhartha Kumar Cc: Vlastimil Babka Cc: Yang Shi Cc: Zach O'Keefe Signed-off-by: Andrew Morton

mm: remove the vma linked list

2022-09-27T02:46:26Z

Replace any vm_next use with vma_find(). Update free_pgtables(), unmap_vmas(), and zap_page_range() to use the maple tree. Use the new free_pgtables() and unmap_vmas() in do_mas_align_munmap(). At the same time, alter the loop to be more compact. Now that free_pgtables() and unmap_vmas() take a maple tree as an argument, rearrange do_mas_align_munmap() to use the new tree to hold the vmas to remove. Remove __vma_link_list() and __vma_unlink_list() as they are exclusively used to update the linked list. Drop linked list update from __insert_vm_struct(). Rework validation of tree as it was depending on the linked list. [yang.lee@linux.alibaba.com: fix one kernel-doc comment] Link: https://bugzilla.openanolis.cn/show_bug.cgi?id=1949 Link: https://lkml.kernel.org/r/20220824021918.94116-1-yang.lee@linux.alibaba.comLink: https://lkml.kernel.org/r/20220906194824.2110408-69-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Signed-off-by: Yang Li Tested-by: Yu Zhao Cc: Catalin Marinas Cc: David Hildenbrand Cc: David Howells Cc: Davidlohr Bueso Cc: "Matthew Wilcox (Oracle)" Cc: SeongJae Park Cc: Sven Schnelle Cc: Vlastimil Babka Cc: Will Deacon Signed-off-by: Andrew Morton

mm: remove vmacache

2022-09-27T02:46:18Z

By using the maple tree and the maple tree state, the vmacache is no longer beneficial and is complicating the VMA code. Remove the vmacache to reduce the work in keeping it up to date and code complexity. Link: https://lkml.kernel.org/r/20220906194824.2110408-26-Liam.Howlett@oracle.com Signed-off-by: Liam R. Howlett Acked-by: Vlastimil Babka Tested-by: Yu Zhao Cc: Catalin Marinas Cc: David Hildenbrand Cc: David Howells Cc: Davidlohr Bueso Cc: "Matthew Wilcox (Oracle)" Cc: SeongJae Park Cc: Sven Schnelle Cc: Will Deacon Signed-off-by: Andrew Morton

mm: unexport page_init_poison

2022-03-25T02:06:45Z

page_init_poison is only used in core MM code, so unexport it. Link: https://lkml.kernel.org/r/20220207063446.1833404-1-hch@lst.de Signed-off-by: Christoph Hellwig Reviewed-by: David Hildenbrand Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: Turn head_compound_mapcount() into folio_entire_mapcount()

2022-03-21T16:59:02Z

Adjust documentation to be more clear. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Christoph Hellwig

mm: Make compound_pincount always available

2022-03-21T16:56:35Z

Move compound_pincount from the third page to the second page, which means it's available for all compound pages. That lets us delete hpage_pincount_available(). On 32-bit systems, there isn't enough space for both compound_pincount and compound_nr in the second page (it would collide with page->private, which is in use for pages in the swap cache), so revert the optimisation of storing both compound_order and compound_nr on 32-bit systems. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: John Hubbard Reviewed-by: Christoph Hellwig Reviewed-by: Jason Gunthorpe Reviewed-by: William Kucharski

mm,fs: split dump_mapping() out from dump_page()

2022-01-15T14:30:26Z

dump_mapping() is a big chunk of dump_page(), and it'd be handy to be able to call it when we don't have a struct page. Split it out and move it to fs/inode.c. Take the opportunity to simplify some of the debug messages a little. Link: https://lkml.kernel.org/r/20211121121056.2870061-1-willy@infradead.org Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: William Kucharski Acked-by: Michal Hocko Cc: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'akpm' (patches from Andrew)

2021-11-06T21:08:17Z

Merge misc updates from Andrew Morton: "257 patches. Subsystems affected by this patch series: scripts, ocfs2, vfs, and mm (slab-generic, slab, slub, kconfig, dax, kasan, debug, pagecache, gup, swap, memcg, pagemap, mprotect, mremap, iomap, tracing, vmalloc, pagealloc, memory-failure, hugetlb, userfaultfd, vmscan, tools, memblock, oom-kill, hugetlbfs, migration, thp, readahead, nommu, ksm, vmstat, madvise, memory-hotplug, rmap, zsmalloc, highmem, zram, cleanups, kfence, and damon)" * emailed patches from Andrew Morton : (257 commits) mm/damon: remove return value from before_terminate callback mm/damon: fix a few spelling mistakes in comments and a pr_debug message mm/damon: simplify stop mechanism Docs/admin-guide/mm/pagemap: wordsmith page flags descriptions Docs/admin-guide/mm/damon/start: simplify the content Docs/admin-guide/mm/damon/start: fix a wrong link Docs/admin-guide/mm/damon/start: fix wrong example commands mm/damon/dbgfs: add adaptive_targets list check before enable monitor_on mm/damon: remove unnecessary variable initialization Documentation/admin-guide/mm/damon: add a document for DAMON_RECLAIM mm/damon: introduce DAMON-based Reclamation (DAMON_RECLAIM) selftests/damon: support watermarks mm/damon/dbgfs: support watermarks mm/damon/schemes: activate schemes based on a watermarks mechanism tools/selftests/damon: update for regions prioritization of schemes mm/damon/dbgfs: support prioritization weights mm/damon/vaddr,paddr: support pageout prioritization mm/damon/schemes: prioritize regions within the quotas mm/damon/selftests: support schemes quotas mm/damon/dbgfs: support quotas of schemes ...

mm/migrate: de-duplicate migrate_reason strings

2021-11-06T20:30:41Z

In order to remove the need to manually keep three different files in synch, provide a common definition of the mapping between enum migrate_reason, and the associated strings for each enum item. 1. Use the tracing system's mapping of enums to strings, by redefining and reusing the MIGRATE_REASON and supporting macros, and using that to populate the string array in mm/debug.c. 2. Move enum migrate_reason to migrate_mode.h. This is not strictly necessary for this patch, but migrate mode and migrate reason go together, so this will slightly clarify things. Link: https://lkml.kernel.org/r/20210922041755.141817-2-jhubbard@nvidia.com Signed-off-by: John Hubbard Reviewed-by: Weizhao Ouyang Cc: "Huang, Ying" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge branch 'per_signal_struct_coredumps-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2021-11-03T19:15:29Z

Pull per signal_struct coredumps from Eric Biederman: "Current coredumps are mixed up with the exit code, the signal handling code, and the ptrace code making coredumps much more complicated than necessary and difficult to follow. This series of changes starts with ptrace_stop and cleans it up, making it easier to follow what is happening in ptrace_stop. Then cleans up the exec interactions with coredumps. Then cleans up the coredump interactions with exit. Finally the coredump interactions with the signal handling code is cleaned up. The first and last changes are bug fixes for minor bugs. I believe the fact that vfork followed by execve can kill the process the called vfork if exec fails is sufficient justification to change the userspace visible behavior. In previous discussions some of these changes were organized differently and individually appeared to make the code base worse. As currently written I believe they all stand on their own as cleanups and bug fixes. Which means that even if the worst should happen and the last change needs to be reverted for some unimaginable reason, the code base will still be improved. If the worst does not happen there are a more cleanups that can be made. Signals that generate coredumps can easily become eligible for short circuit delivery in complete_signal. The entire rendezvous for generating a coredump can move into get_signal. The function force_sig_info_to_task be written in a way that does not modify the signal handling state of the target task (because coredumps are eligible for short circuit delivery). Many of these future cleanups can be done another way but nothing so cleanly as if coredumps become per signal_struct" * 'per_signal_struct_coredumps-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: coredump: Limit coredumps to a single thread group coredump: Don't perform any cleanups before dumping core exit: Factor coredump_exit_mm out of exit_mm exec: Check for a pending fatal signal instead of core_state ptrace: Remove the unnecessary arguments from arch_ptrace_stop signal: Remove the bogus sigkill_pending in ptrace_stop