syzbot


KCSAN: data-race in __delete_from_swap_cache / __try_to_reclaim_swap

Status: upstream: reported on 2024/10/02 07:26
Subsystems: mm
[Documentation on labels]
Reported-by: syzbot+fa43f1b63e3aa6f66329@syzkaller.appspotmail.com
First crash: 3d12h, last: 3d12h
Discussions (2)
Title Replies (including bot) Last reply
[PATCH] mm: swap: prevent possible data-race in __try_to_reclaim_swap 3 (3) 2024/10/04 14:50
[syzbot] [mm?] KCSAN: data-race in __delete_from_swap_cache / __try_to_reclaim_swap 0 (1) 2024/10/02 07:26

Sample crash report:
==================================================================
BUG: KCSAN: data-race in __delete_from_swap_cache / __try_to_reclaim_swap

write to 0xffffea0004c90328 of 8 bytes by task 5186 on cpu 0:
 __delete_from_swap_cache+0x1f0/0x290 mm/swap_state.c:163
 delete_from_swap_cache+0x72/0xe0 mm/swap_state.c:243
 folio_free_swap+0x1d8/0x1f0 mm/swapfile.c:1850
 free_swap_cache mm/swap_state.c:293 [inline]
 free_pages_and_swap_cache+0x1fc/0x410 mm/swap_state.c:325
 __tlb_batch_free_encoded_pages mm/mmu_gather.c:136 [inline]
 tlb_batch_pages_flush mm/mmu_gather.c:149 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:366 [inline]
 tlb_flush_mmu+0x2cf/0x440 mm/mmu_gather.c:373
 zap_pte_range mm/memory.c:1700 [inline]
 zap_pmd_range mm/memory.c:1739 [inline]
 zap_pud_range mm/memory.c:1768 [inline]
 zap_p4d_range mm/memory.c:1789 [inline]
 unmap_page_range+0x1f3c/0x22d0 mm/memory.c:1810
 unmap_single_vma+0x142/0x1d0 mm/memory.c:1856
 unmap_vmas+0x18d/0x2b0 mm/memory.c:1900
 exit_mmap+0x18a/0x690 mm/mmap.c:1864
 __mmput+0x28/0x1b0 kernel/fork.c:1347
 mmput+0x4c/0x60 kernel/fork.c:1369
 exit_mm+0xe4/0x190 kernel/exit.c:571
 do_exit+0x55e/0x17f0 kernel/exit.c:926
 do_group_exit+0x102/0x150 kernel/exit.c:1088
 get_signal+0xf2a/0x1070 kernel/signal.c:2917
 arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x59/0x130 kernel/entry/common.c:218
 do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffea0004c90328 of 8 bytes by task 5189 on cpu 1:
 __try_to_reclaim_swap+0x9d/0x510 mm/swapfile.c:198
 free_swap_and_cache_nr+0x45d/0x8a0 mm/swapfile.c:1915
 zap_pte_range mm/memory.c:1656 [inline]
 zap_pmd_range mm/memory.c:1739 [inline]
 zap_pud_range mm/memory.c:1768 [inline]
 zap_p4d_range mm/memory.c:1789 [inline]
 unmap_page_range+0xcf8/0x22d0 mm/memory.c:1810
 unmap_single_vma+0x142/0x1d0 mm/memory.c:1856
 unmap_vmas+0x18d/0x2b0 mm/memory.c:1900
 exit_mmap+0x18a/0x690 mm/mmap.c:1864
 __mmput+0x28/0x1b0 kernel/fork.c:1347
 mmput+0x4c/0x60 kernel/fork.c:1369
 exit_mm+0xe4/0x190 kernel/exit.c:571
 do_exit+0x55e/0x17f0 kernel/exit.c:926
 __do_sys_exit kernel/exit.c:1055 [inline]
 __se_sys_exit kernel/exit.c:1053 [inline]
 __x64_sys_exit+0x1f/0x20 kernel/exit.c:1053
 x64_sys_call+0x2d46/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:61
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000242 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5189 Comm: syz.1.320 Not tainted 6.12.0-rc1-syzkaller-00031-ge32cde8d2bd7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/10/02 05:39 upstream e32cde8d2bd7 ea2b66a6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in __delete_from_swap_cache / __try_to_reclaim_swap
* Struck through repros no longer work on HEAD.