bisecting fixing commit since 672481c2deffb371d8a7dfdc009e44c09864a869
building syzkaller on 8b96726707a5846209f943c978ccd7eeb1dd6f5e
testing commit 672481c2deffb371d8a7dfdc009e44c09864a869 with gcc (GCC) 8.1.0
kernel signature: 5596fd223dcff3b008a603f813c26f2d4a3ee20c94ccc470aff9428ccab5dbb5
all runs: crashed: WARNING in ext4_set_page_dirty
testing current HEAD d183c8e2647a7d45202c14a33631f6c09020f8ac
testing commit d183c8e2647a7d45202c14a33631f6c09020f8ac with gcc (GCC) 8.1.0
kernel signature: a63cf89fb77ce28eec9c90aae94c3abe103842e00b7a3ba65afdc8aa31d5e4b1
all runs: crashed: WARNING in ext4_set_page_dirty
revisions tested: 2, total time: 26m13.170327545s (build: 18m18.546595435s, test: 6m48.663783218s)
the crash still happens on HEAD
commit msg: Linux 4.19.98
crash: WARNING in ext4_set_page_dirty
audit: type=1800 audit(1579872961.747:41): pid=7435 uid=0 auid=4294967295 ses=4294967295 subj=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 op=collect_data cause=failed comm="syz-executor.1" name="bus" dev="sda1" ino=16550 res=0
WARNING: CPU: 0 PID: 14 at fs/ext4/inode.c:3929 PagePrivate include/linux/page-flags.h:304 [inline]
WARNING: CPU: 0 PID: 14 at fs/ext4/inode.c:3929 ext4_set_page_dirty+0x1be/0x280 fs/ext4/inode.c:3929
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 14 Comm: kworker/0:1 Not tainted 4.19.98-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events xdp_umem_release_deferred
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x123/0x177 lib/dump_stack.c:118
 panic+0x1cd/0x375 kernel/panic.c:186
 __warn.cold.8+0x1b/0x3e kernel/panic.c:541
 report_bug+0x1a4/0x200 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [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:1037
RIP: 0010:ext4_set_page_dirty+0x1be/0x280 fs/ext4/inode.c:3929
Code: c6 00 f9 38 87 48 8d 50 ff a8 01 48 0f 45 da 48 89 df e8 a5 ad b3 ff 0f 0b 48 c7 c6 c0 f7 38 87 48 89 df e8 94 ad b3 ff 0f 0b <0f> 0b eb b3 80 3c 02 00 0f 85 a1 00 00 00 48 8b 43 08 48 c7 c6 00
RSP: 0018:ffff8880a982fbd0 EFLAGS: 00010246
RAX: 00fffe0000000069 RBX: ffffea0001db4880 RCX: 1ffff1100e38c186
RDX: 1ffffd40003b6910 RSI: ffffffff885905e0 RDI: ffffea0001db4880
RBP: ffff8880a982fbe8 R08: fffff940003b2007 R09: fffff940003b2006
R10: fffff940003b2006 R11: ffffea0001d90037 R12: ffffea0001db4880
R13: ffffea0001db4888 R14: ffffffff81d14500 R15: ffffea0001db4880
 set_page_dirty+0x1f3/0x520 mm/page-writeback.c:2569
 set_page_dirty_lock+0x57/0x80 mm/page-writeback.c:2594
 xdp_umem_unpin_pages.isra.5+0xd4/0x2f0 net/xdp/xdp_umem.c:132
 xdp_umem_release net/xdp/xdp_umem.c:162 [inline]
 xdp_umem_release_deferred+0x268/0x3f0 net/xdp/xdp_umem.c:175
 process_one_work+0x830/0x1670 kernel/workqueue.c:2153
 worker_thread+0x85/0xb60 kernel/workqueue.c:2296
 kthread+0x324/0x3e0 kernel/kthread.c:246
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:415
Kernel Offset: disabled
Rebooting in 86400 seconds..