kernel/linux.git/fs/btrfs/compression.c, branch v7.2-rc2

Revert "btrfs: fix the file offset calculation inside btrfs_decompress_buf2page()"

2026-06-09T16:22:44+00:00

It seems that af566bdaff54 was tested against a tree which did not contain commit 12851bd921d4 ("fs: Turn page_offset() into a wrapper around folio_pos()). Unfortunately it has a bug of its own; on 32-bit systems, shifting by PAGE_SHIFT will overflow on files larger than 4GiB. Since page_offset() is now fixed, just revert af566bdaff54. Fixes: af566bdaff54 (btrfs: fix the file offset calculation inside btrfs_decompress_buf2page()) Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Qu Wenruo Reviewed-by: Boris Burkov Tested-by: Boris Burkov Signed-off-by: David Sterba

btrfs: refresh add_ra_bio_pages() to indicate it's using folios

2026-06-08T13:53:31+00:00

The function add_ra_bio_folios() has been utilizing folio interfaces since c808c1dcb1b2 ("btrfs: convert add_ra_bio_pages() to use only folios"), but we are still referring to "pages" inside the function name and all comments. Furthermore, such folio/page mixing can even be confusing, e.g. the variable @page_end is very confusing as we're not really referring to the end of the page, but the end of the folio, especially when we already have large folio support. Enhance that function by: - Rename "page" to "folio" to avoid confusion - Skip to the folio end if there is already a folio in the page cache The existing skip is: cur += folio_size(folio); This is incorrect if @cur is not folio size aligned, and can be common with large folio support. Thankfully this is not going to cause any real bugs, but at most will skip some blocks that can be added to readahead. Signed-off-by: Qu Wenruo Signed-off-by: David Sterba

btrfs: enable cross-folio readahead for bs < ps and large folio cases

2026-06-08T13:53:31+00:00

[BACKGROUND] When bs < ps support was initially introduced, the compressed data readahead was disabled as at that time the target page size was 64K. This means a compressed data extent can span at most 3 64K pages (the head and tail parts are not aligned to 64K), meaning the benefit is pretty minimal. [UNEXPECTED WORKING SITUATION] But with the already merged large folio support, we're already enabling readahead with subpage routine unintentionally, e.g.: 0 4K 8K 12K 16K | Folio 0 | Folio 8K | |<----- Compressed data ------->| We have 2 8K sized folios, all backed by a single compressed data. In that case add_ra_bio_pages() will continue to add folio 8K into the read bio, as the condition to skip is only (bs < ps), not taking the newer large folio support into consideration at all. So for folio 8K, it is added to the read bio, but without subpage lock bitmap populated. Then at end_bbio_data_read(), folio 0 has proper locked bitmap set, but folio 8K does not. This inconsistency is handled by the extra safety net at btrfs_subpage_end_and_test_lock() where if a folio has no @nr_locked, it will just be unlocked without touching the locked bitmap. [ENHANCEMENT] Make add_ra_bio_pages() support bs < ps and large folio cases, by removing the check and calling btrfs_folio_set_lock() unconditionally. This won't make any difference on 4K page sized systems with large folios, as the readahead is already working, although unexpectedly. But this will enable true compressed data readahead for bs < ps cases properly. Please note that such readahead will only work if the compressed extent is crossing folio boundaries, which is also the existing limitation. Signed-off-by: Qu Wenruo Signed-off-by: David Sterba

Merge tag 'for-7.1-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

2026-05-15T20:22:07+00:00

Pull btrfs fixes from David Sterba: - fixup warning when allocating memory for readahead, __GFP_NOWARN was accidentally dropped when setting mapping constraints - in tracepoint of file sync, fix sleeping in atomic context when handling dentries - harden initial loading of block group on crafted/fuzzed images, iterate all chunk mapping entries unconditionally - fix freeing pages of submitted io after checking for errors - fix incorrect inode size after remount when using fallocate KEEP_SIZE mode (also requires disabled 'no-holes' feature) * tag 'for-7.1-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: btrfs: fix incorrect i_size after remount caused by KEEP_SIZE prealloc gap btrfs: only release the dirty pages io tree after successful writes btrfs: tracepoints: fix sleep while in atomic context in btrfs_sync_file() btrfs: always pass __GFP_NOWARN from add_ra_bio_pages() btrfs: fix check_chunk_block_group_mappings() to iterate all chunk maps

btrfs: always pass __GFP_NOWARN from add_ra_bio_pages()

2026-05-07T22:30:53+00:00

A build workload newly prints order-0 allocation failures on 7.1-rc1: sh: page allocation failure: order:0 mode:0x14084a(__GFP_HIGHMEM|__GFP_MOVABLE|__GFP_IO|__GFP_KSWAPD_RECLAIM| __GFP_COMP|__GFP_HARDWALL) CPU: 27 UID: 1000 PID: 855540 Comm: sh Not tainted 7.1.0-rc1-llvm-00058-gdca922e019dd #1 PREEMPTLAZY Call Trace: dump_stack_lvl+0x50/0x70 warn_alloc+0xeb/0x100 __alloc_pages_slowpath+0x567/0x5a0 ? filemap_get_entry+0x11a/0x140 __alloc_frozen_pages_noprof+0x249/0x2d0 alloc_pages_mpol+0xe4/0x180 folio_alloc_noprof+0x80/0xa0 add_ra_bio_pages+0x13c/0x4b0 btrfs_submit_compressed_read+0x229/0x300 submit_one_bio+0x9e/0xe0 btrfs_readahead+0x185/0x1a0 [...] (lldb) source list -a add_ra_bio_pages+0x13c .../vmlinux.unstripped add_ra_bio_pages + 316 at .../fs/btrfs/compression.c:454:8 451 452 folio = filemap_alloc_folio(mapping_gfp_constraint(mapping, constraint_gfp), 453 0, NULL); -> 454 if (!folio) 455 break; I can reproduce this consistently by running a memory hog concurrently with a buffered writer on a machine with a very large amount of swap. Commit 7ae37b2c94ed ("btrfs: prevent direct reclaim during compressed readahead") clearly intended to suppress these warnings. But because the mask set in the address_space with mapping_set_gfp_mask() doesn't include __GFP_NOWARN, mapping_gfp_constraint() removes it from constraint_gfp before it is passed to filemap_alloc_folio(). Fix by refactoring the code to add __GFP_NOWARN after the call to mapping_gfp_constraint(). Fixes: 7ae37b2c94ed ("btrfs: prevent direct reclaim during compressed readahead") Signed-off-by: Calvin Owens Reviewed-by: David Sterba Signed-off-by: David Sterba

Merge tag 'mm-stable-2026-04-13-21-45' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2026-04-15T19:59:16+00:00

Pull MM updates from Andrew Morton: - "maple_tree: Replace big node with maple copy" (Liam Howlett) Mainly prepararatory work for ongoing development but it does reduce stack usage and is an improvement. - "mm, swap: swap table phase III: remove swap_map" (Kairui Song) Offers memory savings by removing the static swap_map. It also yields some CPU savings and implements several cleanups. - "mm: memfd_luo: preserve file seals" (Pratyush Yadav) File seal preservation to LUO's memfd code - "mm: zswap: add per-memcg stat for incompressible pages" (Jiayuan Chen) Additional userspace stats reportng to zswap - "arch, mm: consolidate empty_zero_page" (Mike Rapoport) Some cleanups for our handling of ZERO_PAGE() and zero_pfn - "mm/kmemleak: Improve scan_should_stop() implementation" (Zhongqiu Han) A robustness improvement and some cleanups in the kmemleak code - "Improve khugepaged scan logic" (Vernon Yang) Improve khugepaged scan logic and reduce CPU consumption by prioritizing scanning tasks that access memory frequently - "Make KHO Stateless" (Jason Miu) Simplify Kexec Handover by transitioning KHO from an xarray-based metadata tracking system with serialization to a radix tree data structure that can be passed directly to the next kernel - "mm: vmscan: add PID and cgroup ID to vmscan tracepoints" (Thomas Ballasi and Steven Rostedt) Enhance vmscan's tracepointing - "mm: arch/shstk: Common shadow stack mapping helper and VM_NOHUGEPAGE" (Catalin Marinas) Cleanup for the shadow stack code: remove per-arch code in favour of a generic implementation - "Fix KASAN support for KHO restored vmalloc regions" (Pasha Tatashin) Fix a WARN() which can be emitted the KHO restores a vmalloc area - "mm: Remove stray references to pagevec" (Tal Zussman) Several cleanups, mainly udpating references to "struct pagevec", which became folio_batch three years ago - "mm: Eliminate fake head pages from vmemmap optimization" (Kiryl Shutsemau) Simplify the HugeTLB vmemmap optimization (HVO) by changing how tail pages encode their relationship to the head page - "mm/damon/core: improve DAMOS quota efficiency for core layer filters" (SeongJae Park) Improve two problematic behaviors of DAMOS that makes it less efficient when core layer filters are used - "mm/damon: strictly respect min_nr_regions" (SeongJae Park) Improve DAMON usability by extending the treatment of the min_nr_regions user-settable parameter - "mm/page_alloc: pcp locking cleanup" (Vlastimil Babka) The proper fix for a previously hotfixed SMP=n issue. Code simplifications and cleanups ensued - "mm: cleanups around unmapping / zapping" (David Hildenbrand) A bunch of cleanups around unmapping and zapping. Mostly simplifications, code movements, documentation and renaming of zapping functions - "support batched checking of the young flag for MGLRU" (Baolin Wang) Batched checking of the young flag for MGLRU. It's part cleanups; one benchmark shows large performance benefits for arm64 - "memcg: obj stock and slab stat caching cleanups" (Johannes Weiner) memcg cleanup and robustness improvements - "Allow order zero pages in page reporting" (Yuvraj Sakshith) Enhance free page reporting - it is presently and undesirably order-0 pages when reporting free memory. - "mm: vma flag tweaks" (Lorenzo Stoakes) Cleanup work following from the recent conversion of the VMA flags to a bitmap - "mm/damon: add optional debugging-purpose sanity checks" (SeongJae Park) Add some more developer-facing debug checks into DAMON core - "mm/damon: test and document power-of-2 min_region_sz requirement" (SeongJae Park) An additional DAMON kunit test and makes some adjustments to the addr_unit parameter handling - "mm/damon/core: make passed_sample_intervals comparisons overflow-safe" (SeongJae Park) Fix a hard-to-hit time overflow issue in DAMON core - "mm/damon: improve/fixup/update ratio calculation, test and documentation" (SeongJae Park) A batch of misc/minor improvements and fixups for DAMON - "mm: move vma_(kernel|mmu)_pagesize() out of hugetlb.c" (David Hildenbrand) Fix a possible issue with dax-device when CONFIG_HUGETLB=n. Some code movement was required. - "zram: recompression cleanups and tweaks" (Sergey Senozhatsky) A somewhat random mix of fixups, recompression cleanups and improvements in the zram code - "mm/damon: support multiple goal-based quota tuning algorithms" (SeongJae Park) Extend DAMOS quotas goal auto-tuning to support multiple tuning algorithms that users can select - "mm: thp: reduce unnecessary start_stop_khugepaged()" (Breno Leitao) Fix the khugpaged sysfs handling so we no longer spam the logs with reams of junk when starting/stopping khugepaged - "mm: improve map count checks" (Lorenzo Stoakes) Provide some cleanups and slight fixes in the mremap, mmap and vma code - "mm/damon: support addr_unit on default monitoring targets for modules" (SeongJae Park) Extend the use of DAMON core's addr_unit tunable - "mm: khugepaged cleanups and mTHP prerequisites" (Nico Pache) Cleanups to khugepaged and is a base for Nico's planned khugepaged mTHP support - "mm: memory hot(un)plug and SPARSEMEM cleanups" (David Hildenbrand) Code movement and cleanups in the memhotplug and sparsemem code - "mm: remove CONFIG_ARCH_ENABLE_MEMORY_HOTREMOVE and cleanup CONFIG_MIGRATION" (David Hildenbrand) Rationalize some memhotplug Kconfig support - "change young flag check functions to return bool" (Baolin Wang) Cleanups to change all young flag check functions to return bool - "mm/damon/sysfs: fix memory leak and NULL dereference issues" (Josh Law and SeongJae Park) Fix a few potential DAMON bugs - "mm/vma: convert vm_flags_t to vma_flags_t in vma code" (Lorenzo Stoakes) Convert a lot of the existing use of the legacy vm_flags_t data type to the new vma_flags_t type which replaces it. Mainly in the vma code. - "mm: expand mmap_prepare functionality and usage" (Lorenzo Stoakes) Expand the mmap_prepare functionality, which is intended to replace the deprecated f_op->mmap hook which has been the source of bugs and security issues for some time. Cleanups, documentation, extension of mmap_prepare into filesystem drivers - "mm/huge_memory: refactor zap_huge_pmd()" (Lorenzo Stoakes) Simplify and clean up zap_huge_pmd(). Additional cleanups around vm_normal_folio_pmd() and the softleaf functionality are performed. * tag 'mm-stable-2026-04-13-21-45' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (369 commits) mm: fix deferred split queue races during migration mm/khugepaged: fix issue with tracking lock mm/huge_memory: add and use has_deposited_pgtable() mm/huge_memory: add and use normal_or_softleaf_folio_pmd() mm: add softleaf_is_valid_pmd_entry(), pmd_to_softleaf_folio() mm/huge_memory: separate out the folio part of zap_huge_pmd() mm/huge_memory: use mm instead of tlb->mm mm/huge_memory: remove unnecessary sanity checks mm/huge_memory: deduplicate zap deposited table call mm/huge_memory: remove unnecessary VM_BUG_ON_PAGE() mm/huge_memory: add a common exit path to zap_huge_pmd() mm/huge_memory: handle buggy PMD entry in zap_huge_pmd() mm/huge_memory: have zap_huge_pmd return a boolean, add kdoc mm/huge: avoid big else branch in zap_huge_pmd() mm/huge_memory: simplify vma_is_specal_huge() mm: on remap assert that input range within the proposed VMA mm: add mmap_action_map_kernel_pages[_full]() uio: replace deprecated mmap hook with mmap_prepare in uio_info drivers: hv: vmbus: replace deprecated mmap hook with mmap_prepare mm: allow handling of stacked mmap_prepare hooks in more drivers ...

btrfs: prevent direct reclaim during compressed readahead

2026-04-07T16:56:08+00:00

Under memory pressure, direct reclaim can kick in during compressed readahead. This puts the associated task into D-state. Then shrink_lruvec() disables interrupts when acquiring the LRU lock. Under heavy pressure, we've observed reclaim can run long enough that the CPU becomes prone to CSD lock stalls since it cannot service incoming IPIs. Although the CSD lock stalls are the worst case scenario, we have found many more subtle occurrences of this latency on the order of seconds, over a minute in some cases. Prevent direct reclaim during compressed readahead. This is achieved by using different GFP flags at key points when the bio is marked for readahead. There are two functions that allocate during compressed readahead: btrfs_alloc_compr_folio() and add_ra_bio_pages(). Both currently use GFP_NOFS which includes __GFP_DIRECT_RECLAIM. For the internal API call btrfs_alloc_compr_folio(), the signature changes to accept an additional gfp_t parameter. At the readahead call site, it gets flags similar to GFP_NOFS but stripped of __GFP_DIRECT_RECLAIM. __GFP_NOWARN is added since these allocations are allowed to fail. Demand reads still use full GFP_NOFS and will enter reclaim if needed. All other existing call sites of btrfs_alloc_compr_folio() now explicitly pass GFP_NOFS to retain their current behavior. add_ra_bio_pages() gains a bool parameter which allows callers to specify if they want to allow direct reclaim or not. In either case, the __GFP_NOWARN flag was added unconditionally since the allocations are speculative. There has been some previous work done on calling add_ra_bio_pages() [0]. This patch is complementary: where that patch reduces call frequency, this patch reduces the latency associated with those calls. [0] https://lore.kernel.org/linux-btrfs/656838ec1232314a2657716e59f4f15a8eadba64.1751492111.git.boris@bur.io/ Reviewed-by: Mark Harmstone Reviewed-by: Qu Wenruo Signed-off-by: JP Kobryn (Meta) Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: reduce the size of compressed_bio

2026-04-07T16:55:59+00:00

The member compressed_bio::compressed_len can be replaced by the bio size, as we always submit the full compressed data without any partial read/write. Furthermore we already have enough ASSERT()s making sure the bio size matches the ordered extent or the extent map. This saves 8 bytes from compressed_bio: Before: struct compressed_bio { u64 start; /* 0 8 */ unsigned int len; /* 8 4 */ unsigned int compressed_len; /* 12 4 */ u8 compress_type; /* 16 1 */ bool writeback; /* 17 1 */ /* XXX 6 bytes hole, try to pack */ struct btrfs_bio * orig_bbio; /* 24 8 */ struct btrfs_bio bbio __attribute__((__aligned__(8))); /* 32 304 */ /* XXX last struct has 1 bit hole */ /* size: 336, cachelines: 6, members: 7 */ /* sum members: 330, holes: 1, sum holes: 6 */ /* member types with bit holes: 1, total: 1 */ /* forced alignments: 1 */ /* last cacheline: 16 bytes */ } __attribute__((__aligned__(8))); After: struct compressed_bio { u64 start; /* 0 8 */ unsigned int len; /* 8 4 */ u8 compress_type; /* 12 1 */ bool writeback; /* 13 1 */ /* XXX 2 bytes hole, try to pack */ struct btrfs_bio * orig_bbio; /* 16 8 */ struct btrfs_bio bbio __attribute__((__aligned__(8))); /* 24 304 */ /* XXX last struct has 1 bit hole */ /* size: 328, cachelines: 6, members: 6 */ /* sum members: 326, holes: 1, sum holes: 2 */ /* member types with bit holes: 1, total: 1 */ /* forced alignments: 1 */ /* last cacheline: 8 bytes */ } __attribute__((__aligned__(8))); Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba

btrfs: remove folio parameter from ordered io related functions

2026-04-07T16:55:57+00:00

Both functions btrfs_finish_ordered_extent() and btrfs_mark_ordered_io_finished() are accepting an optional folio parameter. That @folio is passed into can_finish_ordered_extent(), which later will test and clear the ordered flag for the involved range. However I do not think there is any other call site that can clear ordered flags of an page cache folio and can affect can_finish_ordered_extent(). There are limited *_clear_ordered() callers out of can_finish_ordered_extent() function: - btrfs_migrate_folio() This is completely unrelated, it's just migrating the ordered flag to the new folio. - btrfs_cleanup_ordered_extents() We manually clean the ordered flags of all involved folios, then call btrfs_mark_ordered_io_finished() without a @folio parameter. So it doesn't need and didn't pass a @folio parameter in the first place. - btrfs_writepage_fixup_worker() This function is going to be removed soon, and we should not hit that function anymore. - btrfs_invalidate_folio() This is the real call site we need to bother with. If we already have a bio running, btrfs_finish_ordered_extent() in end_bbio_data_write() will be executed first, as btrfs_invalidate_folio() will wait for the writeback to finish. Thus if there is a running bio, it will not see the range has ordered flags, and just skip to the next range. If there is no bio running, meaning the ordered extent is created but the folio is not yet submitted. In that case btrfs_invalidate_folio() will manually clear the folio ordered range, but then manually finish the ordered extent with btrfs_dec_test_ordered_pending() without bothering the folio ordered flags. Meaning if the OE range with folio ordered flags will be finished manually without the need to call can_finish_ordered_extent(). This means all can_finish_ordered_extent() call sites should get a range that has folio ordered flag set, thus the old "return false" branch should never be triggered. Now we can: - Remove the @folio parameter from involved functions * btrfs_mark_ordered_io_finished() * btrfs_finish_ordered_extent() For call sites passing a @folio into those functions, let them manually clear the ordered flag of involved folios. - Move btrfs_finish_ordered_extent() out of the loop in end_bbio_data_write() We only need to call btrfs_finish_ordered_extent() once per bbio, not per folio. - Add an ASSERT() to make sure all folio ranges have ordered flags It's only for end_bbio_data_write(). And we already have enough safe nets to catch over-accounting of ordered extents. Reviewed-by: Filipe Manana Signed-off-by: Qu Wenruo Signed-off-by: David Sterba

folio_batch: rename pagevec.h to folio_batch.h

2026-04-05T20:53:07+00:00

struct pagevec was removed in commit 1e0877d58b1e ("mm: remove struct pagevec"). Rename include/linux/pagevec.h to reflect reality and update includes tree-wide. Add the new filename to MAINTAINERS explicitly, as it no longer matches the "include/linux/page[-_]*" pattern in MEMORY MANAGEMENT - CORE. Link: https://lkml.kernel.org/r/20260225-pagevec_cleanup-v2-3-716868cc2d11@columbia.edu Signed-off-by: Tal Zussman Acked-by: David Hildenbrand (Arm) Reviewed-by: Jan Kara Acked-by: Zi Yan Reviewed-by: Lorenzo Stoakes (Oracle) Cc: Chris Li Cc: Christian Brauner Cc: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton