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ddc4a48797
CMA allocation can fail by temporal page refcount increasement by get_page API as well as get_user_pages friends. However, since get_page is one of the most hot function, it is hard to hook get_page to get callstack everytime due to performance concern. Furthermore, get_page could be nested multiple times so we couldn't track all of the pin sites on limited space of page_pinner. Thus, here approach is keep tracking of put_page callsite rather than get_page once VM found the page migration failed. It's based on assumption: 1. Since it's temporal page refcount, it could be released soon before overflowing dmesg log buffer 2. developer can find the pair of get_page by reviewing put_page. By default, it's eanbled. If you want to disable it: echo 0 > $debugfs/page_pinner/failure_tracking You can capture the tracking using: cat $debugfs/page_pinner/alloc_contig_failed note: the example below is artificial: Page pinned ts 386067292 us count 0 PFN 10162530 Block 9924 type Isolate Flags 0x800000000008000c(uptodate|dirty|swapbacked) __page_pinner_migration_failed+0x30/0x104 putback_lru_page+0x90/0xac putback_movable_pages+0xc4/0x204 __alloc_contig_migrate_range+0x290/0x31c alloc_contig_range+0x114/0x2bc cma_alloc+0x2d8/0x698 cma_alloc_write+0x58/0xb8 simple_attr_write+0xd4/0x124 debugfs_attr_write+0x50/0xd8 full_proxy_write+0x70/0xf8 vfs_write+0x168/0x3a8 ksys_write+0x7c/0xec __arm64_sys_write+0x20/0x30 el0_svc_common+0xa4/0x180 do_el0_svc+0x28/0x88 el0_svc+0x14/0x24 Page pinned ts 385867394 us count 0 PFN 10162530 Block 9924 type Isolate Flags 0x800000000008000c(uptodate|dirty|swapbacked) __page_pinner_migration_failed+0x30/0x104 __alloc_contig_migrate_range+0x200/0x31c alloc_contig_range+0x114/0x2bc cma_alloc+0x2d8/0x698 cma_alloc_write+0x58/0xb8 simple_attr_write+0xd4/0x124 debugfs_attr_write+0x50/0xd8 full_proxy_write+0x70/0xf8 vfs_write+0x168/0x3a8 ksys_write+0x7c/0xec __arm64_sys_write+0x20/0x30 el0_svc_common+0xa4/0x180 do_el0_svc+0x28/0x88 el0_svc+0x14/0x24 el0_sync_handler+0x88/0xec el0_sync+0x198/0x1c0 Bug: 183414571 Signed-off-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Minchan Kim <minchan@google.com> Change-Id: Ie79902c18390eb9f320d823839bb9d9a7fdcdb31 |
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