KCSAN: data-race in __swap_writepage / scan_swap_map

Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in __swap_writepage / scan_swap_map_slots (2) mm				2	89d	90d	27/28	fixed on 2024/08/14 03:44
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BUG: KCSAN: data-race in __swap_writepage / scan_swap_map_slots

read-write to 0xffff888101afd610 of 8 bytes by task 8796 on cpu 0:
 scan_swap_map_slots+0x111b/0x1240
 get_swap_pages+0x31d/0x480 mm/swapfile.c:1097
 folio_alloc_swap+0x3c3/0x4a0 mm/swap_slots.c:343
 shmem_writepage+0x43c/0x970 mm/shmem.c:1492
 pageout mm/vmscan.c:654 [inline]
 shrink_folio_list+0x1952/0x2540 mm/vmscan.c:1315
 reclaim_folio_list+0x7b/0x1d0 mm/vmscan.c:2100
 reclaim_pages+0x220/0x280 mm/vmscan.c:2136
 madvise_cold_or_pageout_pte_range+0xa89/0xb20 mm/madvise.c:526
 walk_pmd_range mm/pagewalk.c:143 [inline]
 walk_pud_range mm/pagewalk.c:221 [inline]
 walk_p4d_range mm/pagewalk.c:256 [inline]
 walk_pgd_range+0x80a/0xec0 mm/pagewalk.c:293
 __walk_page_range+0xc2/0x320 mm/pagewalk.c:395
 walk_page_range+0x2c7/0x3f0 mm/pagewalk.c:521
 madvise_pageout_page_range mm/madvise.c:585 [inline]
 madvise_pageout mm/madvise.c:612 [inline]
 madvise_vma_behavior mm/madvise.c:1031 [inline]
 madvise_walk_vmas mm/madvise.c:1260 [inline]
 do_madvise+0x1b27/0x26f0 mm/madvise.c:1440
 __do_sys_madvise mm/madvise.c:1453 [inline]
 __se_sys_madvise mm/madvise.c:1451 [inline]
 __x64_sys_madvise+0x60/0x70 mm/madvise.c:1451
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff888101afd610 of 8 bytes by task 8804 on cpu 1:
 __swap_writepage+0x7d/0xdb0 mm/page_io.c:383
 swap_writepage+0x6e/0x120 mm/page_io.c:204
 pageout mm/vmscan.c:654 [inline]
 shrink_folio_list+0x1952/0x2540 mm/vmscan.c:1315
 reclaim_folio_list+0x7b/0x1d0 mm/vmscan.c:2100
 reclaim_pages+0x220/0x280 mm/vmscan.c:2136
 madvise_cold_or_pageout_pte_range+0xa89/0xb20 mm/madvise.c:526
 walk_pmd_range mm/pagewalk.c:143 [inline]
 walk_pud_range mm/pagewalk.c:221 [inline]
 walk_p4d_range mm/pagewalk.c:256 [inline]
 walk_pgd_range+0x80a/0xec0 mm/pagewalk.c:293
 __walk_page_range+0xc2/0x320 mm/pagewalk.c:395
 walk_page_range+0x2c7/0x3f0 mm/pagewalk.c:521
 madvise_pageout_page_range mm/madvise.c:585 [inline]
 madvise_pageout mm/madvise.c:612 [inline]
 madvise_vma_behavior mm/madvise.c:1031 [inline]
 madvise_walk_vmas mm/madvise.c:1260 [inline]
 do_madvise+0x1b27/0x26f0 mm/madvise.c:1440
 __do_sys_madvise mm/madvise.c:1453 [inline]
 __se_sys_madvise mm/madvise.c:1451 [inline]
 __x64_sys_madvise+0x60/0x70 mm/madvise.c:1451
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x0000000000008083 -> 0x0000000000004083

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8804 Comm: syz-executor.2 Not tainted 6.7.0-rc8-syzkaller-00055-g5eff55d725a4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
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