bisecting fixing commit since 3c8c23092588a23bf1856a64f58c37f477a413be
building syzkaller on a343ba6b077a3efe7feb57783dcbb7496d2c3572
testing commit 3c8c23092588a23bf1856a64f58c37f477a413be with gcc (GCC) 8.4.1 20210217
kernel signature: 28cd9710460d1843f22e4ba694b0df8616db79c05c8a90d8602bf4ef3fd3f695
run #0: crashed: WARNING in unaccount_page_cache_page
run #1: OK
run #2: OK
run #3: OK
run #4: OK
run #5: OK
run #6: OK
run #7: OK
run #8: OK
run #9: OK
run #10: OK
run #11: OK
run #12: OK
run #13: OK
run #14: OK
run #15: OK
run #16: OK
run #17: OK
run #18: OK
run #19: OK
reproducer seems to be flaky
testing current HEAD eb575cd5d7f60241d016fdd13a9e86d962093c9b
testing commit eb575cd5d7f60241d016fdd13a9e86d962093c9b with gcc (GCC) 8.4.1 20210217
kernel signature: b9f5c6dbd1be476d9494d628056ad2c5dc0b58b0cd8d6e5150c196a619a2a99d
run #0: crashed: WARNING in unaccount_page_cache_page
run #1: OK
run #2: OK
run #3: OK
run #4: OK
run #5: OK
run #6: OK
run #7: OK
run #8: OK
run #9: OK
run #10: OK
run #11: OK
run #12: OK
run #13: OK
run #14: OK
run #15: OK
run #16: OK
run #17: OK
run #18: OK
run #19: OK
Reproducer flagged being flaky
revisions tested: 2, total time: 34m22.30935176s (build: 15m41.466180689s, test: 18m20.765497141s)
the crash still happens on HEAD
commit msg: Linux 4.19.195
crash: WARNING in unaccount_page_cache_page
EXT4-fs error (device loop5): __ext4_new_inode:923: comm syz-executor.5: reserved inode found cleared - inode=1
EXT4-fs error (device loop1): __ext4_new_inode:923: comm syz-executor.1: reserved inode found cleared - inode=1
EXT4-fs error (device loop2): __ext4_new_inode:923: comm syz-executor.2: reserved inode found cleared - inode=1
EXT4-fs (loop5): mount failed
WARNING: CPU: 0 PID: 16708 at mm/filemap.c:250 PageMappedToDisk include/linux/page-flags.h:316 [inline]
WARNING: CPU: 0 PID: 16708 at mm/filemap.c:250 unaccount_page_cache_page+0x56c/0x930 mm/filemap.c:195
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 16708 Comm: syz-executor.5 Not tainted 4.19.195-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x17c/0x226 lib/dump_stack.c:118
 panic+0x1cd/0x375 kernel/panic.c:186
 __warn.cold.7+0x1b/0x36 kernel/panic.c:541
 report_bug+0x1a1/0x200 lib/bug.c:183
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 fixup_bug arch/x86/kernel/traps.c:173 [inline]
 do_error_trap+0x200/0x350 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:316
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:1038
RIP: 0010:unaccount_page_cache_page+0x56c/0x930 mm/filemap.c:250
Code: 0b 80 3c 02 00 0f 85 96 03 00 00 48 8b 43 08 48 c7 c6 e0 0c 10 88 48 8d 50 ff a8 01 48 0f 45 da 48 89 df e8 56 a8 0c 00 0f 0b <0f> 0b 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 80 3c 02
RSP: 0018:ffff88807bfefa00 EFLAGS: 00010002
RAX: 00fff00000001071 RBX: ffffea0002610880 RCX: ffffffff817bccb9
RDX: 1ffffd40004c2110 RSI: ffffffff8810e360 RDI: ffffffff885020c0
RBP: ffff88807bfefa30 R08: fffff940004c2117 R09: fffff940004c2116
R10: fffff940004c2116 R11: ffffea00026108b3 R12: ffffea0002610880
R13: ffffea0002610880 R14: ffff88808ff5bc60 R15: ffffffffffffffff
 delete_from_page_cache_batch+0x178/0xb20 mm/filemap.c:382
 truncate_inode_pages_range+0x443/0x1920 mm/truncate.c:368
 blkdev_fallocate+0x1b3/0x370 fs/block_dev.c:2046
 vfs_fallocate+0x2b5/0x7c0 fs/open.c:308
 ksys_fallocate+0x3c/0x80 fs/open.c:331
 __do_sys_fallocate fs/open.c:339 [inline]
 __se_sys_fallocate fs/open.c:337 [inline]
 __x64_sys_fallocate+0x92/0xf0 fs/open.c:337
 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4665d9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f9e2e832188 EFLAGS: 00000246 ORIG_RAX: 000000000000011d
RAX: ffffffffffffffda RBX: 000000000056c0b0 RCX: 00000000004665d9
RDX: 0000000000000000 RSI: 0000000000000003 RDI: 0000000000000006
RBP: 00000000004bfcb9 R08: 0000000000000000 R09: 0000000000000000
R10: 000000002811fdff R11: 0000000000000246 R12: 000000000056c0b0
R13: 00007ffde0a9168f R14: 00007f9e2e832300 R15: 0000000000022000
Shutting down cpus with NMI
Kernel Offset: disabled
Rebooting in 86400 seconds..