kernel/linux.git/mm/page_io.c, branch linux-7.1.y

mm/page_io: use sio->len for PSWPIN accounting in sio_read_complete()

2026-04-18T07:10:55+00:00

sio_read_complete() uses sio->pages to account global PSWPIN vm events, but sio->pages tracks the number of bvec entries (folios), not base pages. While large folios cannot currently reach this path (SWP_FS_OPS and SWP_SYNCHRONOUS_IO are mutually exclusive, and mTHP swap-in allocation is gated on SWP_SYNCHRONOUS_IO), the accounting is semantically inconsistent with the per-memcg path which correctly uses folio_nr_pages(). Use sio->len >> PAGE_SHIFT instead, which gives the correct base page count since sio->len is accumulated via folio_size(folio). Link: https://lore.kernel.org/20260402061408.36119-1-devnexen@gmail.com Signed-off-by: David Carlier Acked-by: David Hildenbrand (Arm) Cc: Baoquan He Cc: Chris Li Cc: Kairui Song Cc: Kemeng Shi Cc: NeilBrown Cc: Nhat Pham Signed-off-by: Andrew Morton

mm: page_io: prevent memory cgroup release in page_io module

2026-04-18T07:10:45+00:00

In the near future, a folio will no longer pin its corresponding memory cgroup. To ensure safety, it will only be appropriate to hold the rcu read lock or acquire a reference to the memory cgroup returned by folio_memcg(), thereby preventing it from being released. In the current patch, the rcu read lock is employed to safeguard against the release of the memory cgroup in swap_writeout() and bio_associate_blkg_from_page(). This serves as a preparatory measure for the reparenting of the LRU pages. Link: https://lore.kernel.org/7c3708358412fb02c482d0985feb5e9513a863ef.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song Signed-off-by: Qi Zheng Reviewed-by: Harry Yoo Acked-by: Johannes Weiner Acked-by: Shakeel Butt Cc: Allen Pais Cc: Axel Rasmussen Cc: Baoquan He Cc: Chengming Zhou Cc: Chen Ridong Cc: David Hildenbrand Cc: Hamza Mahfooz Cc: Hugh Dickins Cc: Imran Khan Cc: Kamalesh Babulal Cc: Lance Yang Cc: Liam Howlett Cc: Lorenzo Stoakes (Oracle) Cc: Michal Hocko Cc: Michal Koutný Cc: Mike Rapoport Cc: Muchun Song Cc: Nhat Pham Cc: Roman Gushchin Cc: Suren Baghdasaryan Cc: Usama Arif Cc: Vlastimil Babka Cc: Wei Xu Cc: Yosry Ahmed Cc: Yuanchu Xie Cc: Zi Yan Signed-off-by: Andrew Morton

mm: update outdated comments for removed scan_swap_map_slots()

2026-04-05T20:53:35+00:00

The function scan_swap_map_slots() was removed in commit 0ff67f990bd4 ("mm, swap: remove swap slot cache"). The three comments referencing it simply noted that ->flags can be updated non-atomically by scan_swap_map_slots() to justify a data_race() annotation. Since the function no longer exists, drop the parenthetical reference while keeping the data_race() justification intact: ->flags can still be updated non-atomically by other paths (e.g., swapoff clearing SWP_WRITEOK). Assisted-by: unnamed:deepseek-v3.2 coccinelle Link: https://lkml.kernel.org/r/20260321105814.7053-1-kexinsun@smail.nju.edu.cn Signed-off-by: Kexin Sun Acked-by: David Hildenbrand (Arm) Reviewed-by: Lorenzo Stoakes (Oracle) Cc: Axel Rasmussen Cc: Baoquan He Cc: Barry Song Cc: Chris Li Cc: Johannes Weiner Cc: Julia Lawall Cc: Kairui Song Cc: Kemeng Shi Cc: Michal Hocko Cc: Nhat Pham Cc: Qi Zheng Cc: Shakeel Butt Cc: Wei Xu Cc: Yuanchu Xie Signed-off-by: Andrew Morton

mm: fix minor spelling mistakes in comments

2026-01-21T03:24:48+00:00

Correct several typos in comments across files in mm/ [akpm@linux-foundation.org: also fix comment grammar, per SeongJae] Link: https://lkml.kernel.org/r/20251218150906.25042-1-klourencodev@gmail.com Signed-off-by: Kevin Lourenco Reviewed-by: SeongJae Park Acked-by: David Hildenbrand (Red Hat) Reviewed-by: Lorenzo Stoakes Signed-off-by: Andrew Morton

mm, swap: tidy up swap device and cluster info helpers

2025-09-21T21:22:23+00:00

swp_swap_info is the most commonly used helper for retrieving swap info. It has an internal check that may lead to a NULL return value, but almost none of its caller checks the return value, making the internal check pointless. In fact, most of these callers already ensured the entry is valid and never expect a NULL value. Tidy this up and improve the function names. If the caller can make sure the swap entry/type is valid and the device is pinned, use the new introduced __swap_entry_to_info/__swap_type_to_info instead. They have more debug sanity checks and lower overhead as they are inlined. Callers that may expect a NULL value should use swap_entry_to_info/swap_type_to_info instead. No feature change. The rearranged codes should have had no effect, or they should have been hitting NULL de-ref bugs already. Only some new sanity checks are added so potential issues may show up in debug build. The new helpers will be frequently used with swap table later when working with swap cache folios. A locked swap cache folio ensures the entries are valid and stable so these helpers are very helpful. Link: https://lkml.kernel.org/r/20250916160100.31545-8-ryncsn@gmail.com Signed-off-by: Kairui Song Acked-by: Chris Li Reviewed-by: Barry Song Acked-by: David Hildenbrand Suggested-by: Chris Li Cc: Baolin Wang Cc: Baoquan He Cc: "Huang, Ying" Cc: Hugh Dickins Cc: Johannes Weiner Cc: Kemeng Shi Cc: kernel test robot Cc: Lorenzo Stoakes Cc: Matthew Wilcox (Oracle) Cc: Nhat Pham Cc: Yosry Ahmed Cc: Zi Yan Cc: SeongJae Park Signed-off-by: Andrew Morton

mm: stop passing a writeback_control structure to swap_writeout

2025-07-10T05:41:58+00:00

swap_writeout only needs the swap_iocb cookie from the writeback_control structure, so pass it explicitly. Link: https://lkml.kernel.org/r/20250610054959.2057526-6-hch@lst.de Signed-off-by: Christoph Hellwig Cc: Baolin Wang Cc: Chengming Zhou Cc: Hugh Dickins Cc: Johannes Weiner Cc: Matthew Wilcox (Oracle) Cc: Nhat Pham Signed-off-by: Andrew Morton

mm: stop passing a writeback_control structure to __swap_writepage

2025-07-10T05:41:57+00:00

__swap_writepage only needs the swap_iocb cookie from the writeback_control structure, so pass it explicitly and remove the now unused swap_iocb member from struct writeback_control. Link: https://lkml.kernel.org/r/20250610054959.2057526-5-hch@lst.de Signed-off-by: Christoph Hellwig Acked-by: Nhat Pham Cc: Baolin Wang Cc: Chengming Zhou Cc: Hugh Dickins Cc: Johannes Weiner Cc: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton

mm: tidy up swap_writeout

2025-07-10T05:41:57+00:00

Use a goto label to consolidate the unlock folio and return pattern and don't bother with an else after a return / goto. Link: https://lkml.kernel.org/r/20250610054959.2057526-4-hch@lst.de Signed-off-by: Christoph Hellwig Cc: Baolin Wang Cc: Chengming Zhou Cc: Hugh Dickins Cc: Johannes Weiner Cc: Matthew Wilcox (Oracle) Cc: Nhat Pham Signed-off-by: Andrew Morton

mm: Remove swap_writepage() and shmem_writepage()

2025-04-07T07:36:50+00:00

Call swap_writeout() and shmem_writeout() from pageout() instead. Signed-off-by: "Matthew Wilcox (Oracle)" Link: https://lore.kernel.org/r/20250402150005.2309458-9-willy@infradead.org Tested-by: Baolin Wang Reviewed-by: Baolin Wang Signed-off-by: Christian Brauner

page_io: zswap: do not crash the kernel on decompression failure

2025-03-18T05:06:50+00:00

Currently, we crash the kernel when a decompression failure occurs in zswap (either because of memory corruption, or a bug in the compression algorithm). This is overkill. We should only SIGBUS the unfortunate process asking for the zswap entry on zswap load, and skip the corrupted entry in zswap writeback. See [1] for a recent upstream discussion about this. The zswap writeback case is relatively straightforward to fix. For the zswap_load() case, we change the return behavior: * Return 0 on success. * Return -ENOENT (with the folio locked) if zswap does not own the swapped out content. * Return -EIO if zswap owns the swapped out content, but encounters a decompression failure for some reasons. The folio will be unlocked, but not be marked up-to-date, which will eventually cause the process requesting the page to SIGBUS (see the handling of not-up-to-date folio in do_swap_page() in mm/memory.c), without crashing the kernel. * Return -EINVAL if we encounter a large folio, as large folio should not be swapped in while zswap is being used. Similar to the -EIO case, we also unlock the folio but do not mark it as up-to-date to SIGBUS the faulting process. As a side effect, we require one extra zswap tree traversal in the load and writeback paths. Quick benchmarking on a kernel build test shows no performance difference: With the new scheme: real: mean: 125.1s, stdev: 0.12s user: mean: 3265.23s, stdev: 9.62s sys: mean: 2156.41s, stdev: 13.98s The old scheme: real: mean: 125.78s, stdev: 0.45s user: mean: 3287.18s, stdev: 5.95s sys: mean: 2177.08s, stdev: 26.52s [nphamcs@gmail.com: fix documentation of zswap_load()] Link: https://lkml.kernel.org/r/20250306222453.1269456-1-nphamcs@gmail.com Link: https://lore.kernel.org/all/ZsiLElTykamcYZ6J@casper.infradead.org/ [1] Link: https://lkml.kernel.org/r/20250306205011.784787-1-nphamcs@gmail.com Signed-off-by: Nhat Pham Suggested-by: Matthew Wilcox Suggested-by: Yosry Ahmed Suggested-by: Johannes Weiner Reviewed-by: Chengming Zhou Acked-by: Johannes Weiner Signed-off-by: Andrew Morton