MIME-Version: 1.0
Date:   Thu, 18 Nov 2021 06:20:26 -0800
Message-ID: <00000000000020805d05d110dc77@google.com>
Subject: [syzbot] KCSAN: data-race in flush_tlb_batched_pending / try_to_unmap_one
From:   syzbot <syzbot+aa5bebed695edaccf0df@syzkaller.appspotmail.com>
To:     akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, syzkaller-bugs@googlegroups.com
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Hello,

syzbot found the following issue on:

HEAD commit:    42eb8fdac2fc Merge tag 'gfs2-v5.16-rc2-fixes' of git://git..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13160026b00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a70237460d215073
dashboard link: https://syzkaller.appspot.com/bug?extid=aa5bebed695edaccf0df
compiler:       Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+aa5bebed695edaccf0df@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in flush_tlb_batched_pending / try_to_unmap_one

write to 0xffff8881072cfbbc of 1 bytes by task 17406 on cpu 1:
 flush_tlb_batched_pending+0x5f/0x80 mm/rmap.c:691
 madvise_free_pte_range+0xee/0x7d0 mm/madvise.c:594
 walk_pmd_range mm/pagewalk.c:128 [inline]
 walk_pud_range mm/pagewalk.c:205 [inline]
 walk_p4d_range mm/pagewalk.c:240 [inline]
 walk_pgd_range mm/pagewalk.c:277 [inline]
 __walk_page_range+0x981/0x1160 mm/pagewalk.c:379
 walk_page_range+0x131/0x300 mm/pagewalk.c:475
 madvise_free_single_vma mm/madvise.c:734 [inline]
 madvise_dontneed_free mm/madvise.c:822 [inline]
 madvise_vma mm/madvise.c:996 [inline]
 do_madvise+0xe4a/0x1140 mm/madvise.c:1202
 __do_sys_madvise mm/madvise.c:1228 [inline]
 __se_sys_madvise mm/madvise.c:1226 [inline]
 __x64_sys_madvise+0x5d/0x70 mm/madvise.c:1226
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

write to 0xffff8881072cfbbc of 1 bytes by task 71 on cpu 0:
 set_tlb_ubc_flush_pending mm/rmap.c:636 [inline]
 try_to_unmap_one+0x60e/0x1220 mm/rmap.c:1515
 rmap_walk_anon+0x2fb/0x470 mm/rmap.c:2301
 try_to_unmap+0xec/0x110
 shrink_page_list+0xe91/0x2620 mm/vmscan.c:1719
 shrink_inactive_list+0x3fb/0x730 mm/vmscan.c:2394
 shrink_list mm/vmscan.c:2621 [inline]
 shrink_lruvec+0x3c9/0x710 mm/vmscan.c:2940
 shrink_node_memcgs+0x23e/0x410 mm/vmscan.c:3129
 shrink_node+0x8f6/0x1190 mm/vmscan.c:3252
 kswapd_shrink_node mm/vmscan.c:4022 [inline]
 balance_pgdat+0x702/0xd30 mm/vmscan.c:4213
 kswapd+0x200/0x340 mm/vmscan.c:4473
 kthread+0x2c7/0x2e0 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30

value changed: 0x01 -> 0x00

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 71 Comm: kswapd0 Not tainted 5.16.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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