kernel/linux.git/include/linux/compaction.h, branch v6.6.131

NFS: fix nfs_release_folio() to not deadlock via kcompactd writeback

2025-03-13T11:58:27+00:00

commit ce6d9c1c2b5cc785016faa11b48b6cd317eb367e upstream. Add PF_KCOMPACTD flag and current_is_kcompactd() helper to check for it so nfs_release_folio() can skip calling nfs_wb_folio() from kcompactd. Otherwise NFS can deadlock waiting for kcompactd enduced writeback which recurses back to NFS (which triggers writeback to NFSD via NFS loopback mount on the same host, NFSD blocks waiting for XFS's call to __filemap_get_folio): 6070.550357] INFO: task kcompactd0:58 blocked for more than 4435 seconds. {--- [58] "kcompactd0" [<0>] folio_wait_bit+0xe8/0x200 [<0>] folio_wait_writeback+0x2b/0x80 [<0>] nfs_wb_folio+0x80/0x1b0 [nfs] [<0>] nfs_release_folio+0x68/0x130 [nfs] [<0>] split_huge_page_to_list_to_order+0x362/0x840 [<0>] migrate_pages_batch+0x43d/0xb90 [<0>] migrate_pages_sync+0x9a/0x240 [<0>] migrate_pages+0x93c/0x9f0 [<0>] compact_zone+0x8e2/0x1030 [<0>] compact_node+0xdb/0x120 [<0>] kcompactd+0x121/0x2e0 [<0>] kthread+0xcf/0x100 [<0>] ret_from_fork+0x31/0x40 [<0>] ret_from_fork_asm+0x1a/0x30 ---} [akpm@linux-foundation.org: fix build] Link: https://lkml.kernel.org/r/20250225022002.26141-1-snitzer@kernel.org Fixes: 96780ca55e3c ("NFS: fix up nfs_release_folio() to try to release the page") Signed-off-by: Mike Snitzer Cc: Anna Schumaker Cc: Trond Myklebust Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

mm: compaction: mark kcompactd_run() and kcompactd_stop() __meminit

2023-06-19T23:19:28+00:00

Add __meminit to kcompactd_run() and kcompactd_stop() to ensure they're default to __init when memory hotplug is not enabled. Link: https://lkml.kernel.org/r/20230610034615.997813-1-linmiaohe@huawei.com Signed-off-by: Miaohe Lin Reviewed-by: Baolin Wang Signed-off-by: Andrew Morton

mm: compaction: have compaction_suitable() return bool

2023-06-09T23:25:37+00:00

Since it only returns COMPACT_CONTINUE or COMPACT_SKIPPED now, a bool return value simplifies the callsites. Link: https://lkml.kernel.org/r/20230602151204.GD161817@cmpxchg.org Signed-off-by: Johannes Weiner Suggested-by: Vlastimil Babka Acked-by: Vlastimil Babka Cc: Baolin Wang Cc: Mel Gorman Cc: Michal Hocko Signed-off-by: Andrew Morton

mm: compaction: refactor __compaction_suitable()

2023-06-09T23:25:36+00:00

__compaction_suitable() is supposed to check for available migration targets. However, it also checks whether the operation was requested via /proc/sys/vm/compact_memory, and whether the original allocation request can already succeed. These don't apply to all callsites. Move the checks out to the callers, so that later patches can deal with them one by one. No functional change intended. [hannes@cmpxchg.org: fix comment, per Vlastimil] Link: https://lkml.kernel.org/r/20230602144942.GC161817@cmpxchg.org Link: https://lkml.kernel.org/r/20230519123959.77335-4-hannes@cmpxchg.org Signed-off-by: Johannes Weiner Acked-by: Vlastimil Babka Cc: Mel Gorman Cc: Michal Hocko Signed-off-by: Andrew Morton

mm: compaction: remove compaction result helpers

2023-06-09T23:25:36+00:00

Patch series "mm: compaction: cleanups & simplifications". These compaction cleanups are split out from the huge page allocator series[1], as requested by reviewer feedback. [1] https://lore.kernel.org/linux-mm/20230418191313.268131-1-hannes@cmpxchg.org/ This patch (of 5): The compaction result helpers encode quirks that are specific to the allocator's retry logic. E.g. COMPACT_SUCCESS and COMPACT_COMPLETE actually represent failures that should be retried upon, and so on. I frequently found myself pulling up the helper implementation in order to understand and work on the retry logic. They're not quite clean abstractions; rather they split the retry logic into two locations. Remove the helpers and inline the checks. Then comment on the result interpretations directly where the decision making happens. Link: https://lkml.kernel.org/r/20230519123959.77335-1-hannes@cmpxchg.org Link: https://lkml.kernel.org/r/20230519123959.77335-2-hannes@cmpxchg.org Signed-off-by: Johannes Weiner Acked-by: Vlastimil Babka Cc: Mel Gorman Cc: Michal Hocko Signed-off-by: Andrew Morton

mm: compaction: move compaction sysctl to its own file

2023-04-13T18:49:35+00:00

This moves all compaction sysctls to its own file. Move sysctl to where the functionality truly belongs to improve readability, reduce merge conflicts, and facilitate maintenance. I use x86_defconfig and linux-next-20230327 branch $ make defconfig;make all -jn CONFIG_COMPACTION=y add/remove: 1/0 grow/shrink: 1/1 up/down: 350/-256 (94) Function old new delta vm_compaction - 320 +320 kcompactd_init 180 210 +30 vm_table 2112 1856 -256 Total: Before=21119987, After=21120081, chg +0.00% Despite the addition of 94 bytes the patch still seems a worthwile cleanup. Link: https://lore.kernel.org/lkml/067f7347-ba10-5405-920c-0f5f985c84f4@suse.cz/ Signed-off-by: Minghao Chi Acked-by: Vlastimil Babka Signed-off-by: Luis Chamberlain

mm: compaction: remove unneeded return value of kcompactd_run

2022-04-29T06:16:17+00:00

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.com Signed-off-by: Miaohe Lin Cc; Mel Gorman Cc: David Hildenbrand Cc: Vlastimil Babka Cc: Pintu Kumar Cc: Charan Teja Kalla Signed-off-by: Andrew Morton

mm: compaction: support triggering of proactive compaction by user

2021-09-03T16:58:17+00:00

The proactive compaction[1] gets triggered for every 500msec and run compaction on the node for COMPACTION_HPAGE_ORDER (usually order-9) pages based on the value set to sysctl.compaction_proactiveness. Triggering the compaction for every 500msec in search of COMPACTION_HPAGE_ORDER pages is not needed for all applications, especially on the embedded system usecases which may have few MB's of RAM. Enabling the proactive compaction in its state will endup in running almost always on such systems. Other side, proactive compaction can still be very much useful for getting a set of higher order pages in some controllable manner(controlled by using the sysctl.compaction_proactiveness). So, on systems where enabling the proactive compaction always may proove not required, can trigger the same from user space on write to its sysctl interface. As an example, say app launcher decide to launch the memory heavy application which can be launched fast if it gets more higher order pages thus launcher can prepare the system in advance by triggering the proactive compaction from userspace. This triggering of proactive compaction is done on a write to sysctl.compaction_proactiveness by user. [1]https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=facdaa917c4d5a376d09d25865f5a863f906234a [akpm@linux-foundation.org: tweak vm.rst, per Mike] Link: https://lkml.kernel.org/r/1627653207-12317-1-git-send-email-charante@codeaurora.org Signed-off-by: Charan Teja Reddy Acked-by: Vlastimil Babka Acked-by: Rafael Aquini Cc: Mike Rapoport Cc: Luis Chamberlain Cc: Kees Cook Cc: Iurii Zaikin Cc: Dave Hansen Cc: Mel Gorman Cc: Nitin Gupta Cc: Jonathan Corbet Cc: Khalid Aziz Cc: David Rientjes Cc: Vinayak Menon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: fix spelling mistakes in header files

2021-07-08T18:48:21+00:00

Fix some spelling mistakes in comments: successfull ==> successful potentialy ==> potentially alloced ==> allocated indicies ==> indices wont ==> won't resposible ==> responsible dirtyness ==> dirtiness droppped ==> dropped alread ==> already occured ==> occurred interupts ==> interrupts extention ==> extension slighly ==> slightly Dont't ==> Don't Link: https://lkml.kernel.org/r/20210531034849.9549-2-thunder.leizhen@huawei.com Signed-off-by: Zhen Lei Cc: Jerome Glisse Cc: Mike Kravetz Cc: Dennis Zhou Cc: Tejun Heo Cc: Christoph Lameter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/compaction: remove unused variable sysctl_compact_memory

2021-05-05T18:27:24+00:00

The sysctl_compact_memory is mostly unused in mm/compaction.c It just acts as a place holder for sysctl to store .data. But the .data itself is not needed here. So we can get ride of this variable completely and make .data as NULL. This will also eliminate the extern declaration from header file. No functionality is broken or changed this way. Link: https://lkml.kernel.org/r/1614852224-14671-1-git-send-email-pintu@codeaurora.org Signed-off-by: Pintu Kumar Signed-off-by: Pintu Agarwal Reviewed-by: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds