lwn.git/mm, branch v6.8-rc3

Merge tag 'mm-hotfixes-stable-2024-01-28-23-21' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2024-01-30T01:12:16+00:00

Pull misc fixes from Andrew Morton: "22 hotfixes. 11 are cc:stable and the remainder address post-6.7 issues or aren't considered appropriate for backporting" * tag 'mm-hotfixes-stable-2024-01-28-23-21' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (22 commits) mm: thp_get_unmapped_area must honour topdown preference mm: huge_memory: don't force huge page alignment on 32 bit userfaultfd: fix mmap_changing checking in mfill_atomic_hugetlb selftests/mm: ksm_tests should only MADV_HUGEPAGE valid memory scs: add CONFIG_MMU dependency for vfree_atomic() mm/memory: fix folio_set_dirty() vs. folio_mark_dirty() in zap_pte_range() mm/huge_memory: fix folio_set_dirty() vs. folio_mark_dirty() selftests/mm: Update va_high_addr_switch.sh to check CPU for la57 flag selftests: mm: fix map_hugetlb failure on 64K page size systems MAINTAINERS: supplement of zswap maintainers update stackdepot: make fast paths lock-less again stackdepot: add stats counters exported via debugfs mm, kmsan: fix infinite recursion due to RCU critical section mm/writeback: fix possible divide-by-zero in wb_dirty_limits(), again selftests/mm: switch to bash from sh MAINTAINERS: add man-pages git trees mm: memcontrol: don't throttle dying tasks on memory.high mm: mmap: map MAP_STACK to VM_NOHUGEPAGE uprobes: use pagesize-aligned virtual address when replacing pages selftests/mm: mremap_test: fix build warning ...

Merge tag 'fixes-2024-01-28' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock

2024-01-28T17:41:39+00:00

Pull memblock fix from Mike Rapoport: "Fix crash when reserved memory is not added to memory. When CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled, the initialization of reserved pages may cause access of NODE_DATA() with invalid nid and crash. Add a fall back to early_pfn_to_nid() in memmap_init_reserved_pages() to ensure a valid node id is always passed to init_reserved_page()" * tag 'fixes-2024-01-28' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock: memblock: fix crash when reserved memory is not added to memory

mm: thp_get_unmapped_area must honour topdown preference

2024-01-26T09:23:44+00:00

The addition of commit efa7df3e3bb5 ("mm: align larger anonymous mappings on THP boundaries") caused the "virtual_address_range" mm selftest to start failing on arm64. Let's fix that regression. There were 2 visible problems when running the test; 1) it takes much longer to execute, and 2) the test fails. Both are related: The (first part of the) test allocates as many 1GB anonymous blocks as it can in the low 256TB of address space, passing NULL as the addr hint to mmap. Before the faulty patch, all allocations were abutted and contained in a single, merged VMA. However, after this patch, each allocation is in its own VMA, and there is a 2M gap between each VMA. This causes the 2 problems in the test: 1) mmap becomes MUCH slower because there are so many VMAs to check to find a new 1G gap. 2) mmap fails once it hits the VMA limit (/proc/sys/vm/max_map_count). Hitting this limit then causes a subsequent calloc() to fail, which causes the test to fail. The problem is that arm64 (unlike x86) selects ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT. But __thp_get_unmapped_area() allocates len+2M then always aligns to the bottom of the discovered gap. That causes the 2M hole. Fix this by detecting cases where we can still achive the alignment goal when moved to the top of the allocated area, if configured to prefer top-down allocation. While we are at it, fix thp_get_unmapped_area's use of pgoff, which should always be zero for anonymous mappings. Prior to the faulty change, while it was possible for user space to pass in pgoff!=0, the old mm->get_unmapped_area() handler would not use it. thp_get_unmapped_area() does use it, so let's explicitly zero it before calling the handler. This should also be the correct behavior for arches that define their own get_unmapped_area() handler. Link: https://lkml.kernel.org/r/20240123171420.3970220-1-ryan.roberts@arm.com Fixes: efa7df3e3bb5 ("mm: align larger anonymous mappings on THP boundaries") Closes: https://lore.kernel.org/linux-mm/1e8f5ac7-54ce-433a-ae53-81522b2320e1@arm.com/ Signed-off-by: Ryan Roberts Reviewed-by: Yang Shi Cc: Matthew Wilcox (Oracle) Cc: Rik van Riel Cc: Signed-off-by: Andrew Morton

mm: huge_memory: don't force huge page alignment on 32 bit

2024-01-26T07:52:21+00:00

commit efa7df3e3bb5 ("mm: align larger anonymous mappings on THP boundaries") caused two issues [1] [2] reported on 32 bit system or compat userspace. It doesn't make too much sense to force huge page alignment on 32 bit system due to the constrained virtual address space. [1] https://lore.kernel.org/linux-mm/d0a136a0-4a31-46bc-adf4-2db109a61672@kernel.org/ [2] https://lore.kernel.org/linux-mm/CAJuCfpHXLdQy1a2B6xN2d7quTYwg2OoZseYPZTRpU0eHHKD-sQ@mail.gmail.com/ Link: https://lkml.kernel.org/r/20240118180505.2914778-1-shy828301@gmail.com Fixes: efa7df3e3bb5 ("mm: align larger anonymous mappings on THP boundaries") Signed-off-by: Yang Shi Reported-by: Jiri Slaby Reported-by: Suren Baghdasaryan Tested-by: Jiri Slaby Tested-by: Suren Baghdasaryan Reviewed-by: Matthew Wilcox (Oracle) Cc: Rik van Riel Cc: Christopher Lameter Signed-off-by: Andrew Morton

userfaultfd: fix mmap_changing checking in mfill_atomic_hugetlb

2024-01-26T07:52:21+00:00

In mfill_atomic_hugetlb(), mmap_changing isn't being checked again if we drop mmap_lock and reacquire it. When the lock is not held, mmap_changing could have been incremented. This is also inconsistent with the behavior in mfill_atomic(). Link: https://lkml.kernel.org/r/20240117223729.1444522-1-lokeshgidra@google.com Fixes: df2cc96e77011 ("userfaultfd: prevent non-cooperative events vs mcopy_atomic races") Signed-off-by: Lokesh Gidra Cc: Andrea Arcangeli Cc: Mike Rapoport Cc: Axel Rasmussen Cc: Brian Geffon Cc: David Hildenbrand Cc: Jann Horn Cc: Kalesh Singh Cc: Matthew Wilcox (Oracle) Cc: Nicolas Geoffray Cc: Peter Xu Cc: Suren Baghdasaryan Cc: Signed-off-by: Andrew Morton

mm/memory: fix folio_set_dirty() vs. folio_mark_dirty() in zap_pte_range()

2024-01-26T07:52:21+00:00

The correct folio replacement for "set_page_dirty()" is "folio_mark_dirty()", not "folio_set_dirty()". Using the latter won't properly inform the FS using the dirty_folio() callback. This has been found by code inspection, but likely this can result in some real trouble when zapping dirty PTEs that point at clean pagecache folios. Yuezhang Mo said: "Without this fix, testing the latest exfat with xfstests, test cases generic/029 and generic/030 will fail." Link: https://lkml.kernel.org/r/20240122171751.272074-1-david@redhat.com Fixes: c46265030b0f ("mm/memory: page_remove_rmap() -> folio_remove_rmap_pte()") Signed-off-by: David Hildenbrand Reported-by: Ryan Roberts Closes: https://lkml.kernel.org/r/2445cedb-61fb-422c-8bfb-caf0a2beed62@arm.com Reviewed-by: Ryan Roberts Cc: Matthew Wilcox (Oracle) Reviewed-by: Yuezhang Mo Signed-off-by: Andrew Morton

mm/huge_memory: fix folio_set_dirty() vs. folio_mark_dirty()

2024-01-26T07:52:21+00:00

mm/writeback: fix possible divide-by-zero in wb_dirty_limits(), again

2024-01-26T07:52:20+00:00

(struct dirty_throttle_control *)->thresh is an unsigned long, but is passed as the u32 divisor argument to div_u64(). On architectures where unsigned long is 64 bytes, the argument will be implicitly truncated. Use div64_u64() instead of div_u64() so that the value used in the "is this a safe division" check is the same as the divisor. Also, remove redundant cast of the numerator to u64, as that should happen implicitly. This would be difficult to exploit in memcg domain, given the ratio-based arithmetic domain_drity_limits() uses, but is much easier in global writeback domain with a BDI_CAP_STRICTLIMIT-backing device, using e.g. vm.dirty_bytes=(1<<32)*PAGE_SIZE so that dtc->thresh == (1<<32) Link: https://lkml.kernel.org/r/20240118181954.1415197-1-zokeefe@google.com Fixes: f6789593d5ce ("mm/page-writeback.c: fix divide by zero in bdi_dirty_limits()") Signed-off-by: Zach O'Keefe Cc: Maxim Patlasov Cc: Signed-off-by: Andrew Morton

mm: memcontrol: don't throttle dying tasks on memory.high

2024-01-26T07:52:20+00:00

While investigating hosts with high cgroup memory pressures, Tejun found culprit zombie tasks that had were holding on to a lot of memory, had SIGKILL pending, but were stuck in memory.high reclaim. In the past, we used to always force-charge allocations from tasks that were exiting in order to accelerate them dying and freeing up their rss. This changed for memory.max in a4ebf1b6ca1e ("memcg: prohibit unconditional exceeding the limit of dying tasks"); it noted that this can cause (userspace inducable) containment failures, so it added a mandatory reclaim and OOM kill cycle before forcing charges. At the time, memory.high enforcement was handled in the userspace return path, which isn't reached by dying tasks, and so memory.high was still never enforced by dying tasks. When c9afe31ec443 ("memcg: synchronously enforce memory.high for large overcharges") added synchronous reclaim for memory.high, it added unconditional memory.high enforcement for dying tasks as well. The callstack shows that this path is where the zombie is stuck in. We need to accelerate dying tasks getting past memory.high, but we cannot do it quite the same way as we do for memory.max: memory.max is enforced strictly, and tasks aren't allowed to move past it without FIRST reclaiming and OOM killing if necessary. This ensures very small levels of excess. With memory.high, though, enforcement happens lazily after the charge, and OOM killing is never triggered. A lot of concurrent threads could have pushed, or could actively be pushing, the cgroup into excess. The dying task will enter reclaim on every allocation attempt, with little hope of restoring balance. To fix this, skip synchronous memory.high enforcement on dying tasks altogether again. Update memory.high path documentation while at it. [hannes@cmpxchg.org: also handle tasks are being killed during the reclaim] Link: https://lkml.kernel.org/r/20240111192807.GA424308@cmpxchg.org Link: https://lkml.kernel.org/r/20240111132902.389862-1-hannes@cmpxchg.org Fixes: c9afe31ec443 ("memcg: synchronously enforce memory.high for large overcharges") Signed-off-by: Johannes Weiner Reported-by: Tejun Heo Reviewed-by: Yosry Ahmed Acked-by: Shakeel Butt Acked-by: Roman Gushchin Cc: Dan Schatzberg Cc: Michal Hocko Cc: Muchun Song Signed-off-by: Andrew Morton

fs/hugetlbfs/inode.c: mm/memory-failure.c: fix hugetlbfs hwpoison handling

2024-01-26T07:52:20+00:00

has_extra_refcount() makes the assumption that the page cache adds a ref count of 1 and subtracts this in the extra_pins case. Commit a08c7193e4f1 (mm/filemap: remove hugetlb special casing in filemap.c) modifies __filemap_add_folio() by calling folio_ref_add(folio, nr); for all cases (including hugtetlb) where nr is the number of pages in the folio. We should adjust the number of references coming from the page cache by subtracing the number of pages rather than 1. In hugetlbfs_read_iter(), folio_test_has_hwpoisoned() is testing the wrong flag as, in the hugetlb case, memory-failure code calls folio_test_set_hwpoison() to indicate poison. folio_test_hwpoison() is the correct function to test for that flag. After these fixes, the hugetlb hwpoison read selftest passes all cases. Link: https://lkml.kernel.org/r/20240112180840.367006-1-sidhartha.kumar@oracle.com Fixes: a08c7193e4f1 ("mm/filemap: remove hugetlb special casing in filemap.c") Signed-off-by: Sidhartha Kumar Closes: https://lore.kernel.org/linux-mm/20230713001833.3778937-1-jiaqiyan@google.com/T/#m8e1469119e5b831bbd05d495f96b842e4a1c5519 Reported-by: Muhammad Usama Anjum Tested-by: Muhammad Usama Anjum Acked-by: Miaohe Lin Acked-by: Muchun Song Cc: James Houghton Cc: Jiaqi Yan Cc: Matthew Wilcox (Oracle) Cc: Naoya Horiguchi Cc: [6.7+] Signed-off-by: Andrew Morton