On Mon, Feb 27, 2017 at 6:11 PM, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: > Hello, > > The following program triggers GPF in bdi_put: > https://gist.githubusercontent.com/dvyukov/15b3e211f937ff6abc558724369066ce/raw/cc017edf57963e30175a6a6fe2b8d917f6e92899/gistfile1.txt > > general protection fault: 0000 [#1] SMP KASAN > Modules linked in: > CPU: 0 PID: 2952 Comm: a.out Not tainted 4.10.0+ #229 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 > task: ffff880063e72180 task.stack: ffff880064a78000 > RIP: 0010:__read_once_size include/linux/compiler.h:247 [inline] > RIP: 0010:atomic_read arch/x86/include/asm/atomic.h:26 [inline] > RIP: 0010:refcount_sub_and_test include/linux/refcount.h:156 [inline] > RIP: 0010:refcount_dec_and_test include/linux/refcount.h:181 [inline] > RIP: 0010:kref_put include/linux/kref.h:71 [inline] > RIP: 0010:bdi_put+0x8b/0x1d0 mm/backing-dev.c:914 > RSP: 0018:ffff880064a7f0b0 EFLAGS: 00010202 > RAX: 0000000000000007 RBX: 0000000000000000 RCX: 0000000000000000 > RDX: ffff880064a7f118 RSI: 0000000000000001 RDI: 0000000000000000 > RBP: ffff880064a7f140 R08: ffff880065603280 R09: 0000000000000001 > R10: 0000000000000000 R11: 0000000000000001 R12: dffffc0000000000 > R13: 0000000000000038 R14: 1ffff1000c94fe17 R15: ffff880064a7f218 > FS: 0000000000eb5880(0000) GS:ffff88006d000000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000020914ffa CR3: 000000006bc37000 CR4: 00000000001426f0 > Call Trace: > bdev_evict_inode+0x203/0x3a0 fs/block_dev.c:888 > evict+0x46e/0x980 fs/inode.c:553 > iput_final fs/inode.c:1515 [inline] > iput+0x589/0xb20 fs/inode.c:1542 > dentry_unlink_inode+0x43b/0x600 fs/dcache.c:343 > __dentry_kill+0x34d/0x740 fs/dcache.c:538 > dentry_kill fs/dcache.c:579 [inline] > dput.part.27+0x5ce/0x7c0 fs/dcache.c:791 > dput fs/dcache.c:753 [inline] > do_one_tree+0x43/0x50 fs/dcache.c:1454 > shrink_dcache_for_umount+0xbb/0x2b0 fs/dcache.c:1468 > generic_shutdown_super+0xcd/0x4c0 fs/super.c:421 > kill_anon_super+0x3c/0x50 fs/super.c:988 > deactivate_locked_super+0x88/0xd0 fs/super.c:309 > deactivate_super+0x155/0x1b0 fs/super.c:340 > cleanup_mnt+0xb2/0x160 fs/namespace.c:1112 > __cleanup_mnt+0x16/0x20 fs/namespace.c:1119 > task_work_run+0x18a/0x260 kernel/task_work.c:116 > tracehook_notify_resume include/linux/tracehook.h:191 [inline] > exit_to_usermode_loop+0x23b/0x2a0 arch/x86/entry/common.c:160 > prepare_exit_to_usermode arch/x86/entry/common.c:190 [inline] > syscall_return_slowpath+0x4d3/0x570 arch/x86/entry/common.c:259 > entry_SYSCALL_64_fastpath+0xc0/0xc2 > RIP: 0033:0x435e19 > RSP: 002b:00007ffc9d7f2748 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 > RAX: ffffffffffffffea RBX: 0100000000000000 RCX: 0000000000435e19 > RDX: 0000000020063000 RSI: 0000000020914ffa RDI: 0000000020037000 > RBP: 00007ffc9d7f2fe0 R08: 0000000020039000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > R13: 0000000000402b70 R14: 0000000000402c00 R15: 0000000000000000 > Code: 04 f2 f2 f2 c7 40 08 f3 f3 f3 f3 e8 f0 ec de ff 48 8d 45 98 48 > 8b 95 70 ff ff ff 48 c1 e8 03 42 c6 04 20 04 4c 89 e8 48 c1 e8 03 <42> > 0f b6 0c 20 4c 89 e8 83 e0 07 83 c0 03 38 c8 7c 08 84 c9 0f > RIP: __read_once_size include/linux/compiler.h:247 [inline] RSP: > ffff880064a7f0b0 > RIP: atomic_read arch/x86/include/asm/atomic.h:26 [inline] RSP: ffff880064a7f0b0 > RIP: refcount_sub_and_test include/linux/refcount.h:156 [inline] RSP: > ffff880064a7f0b0 > RIP: refcount_dec_and_test include/linux/refcount.h:181 [inline] RSP: > ffff880064a7f0b0 > RIP: kref_put include/linux/kref.h:71 [inline] RSP: ffff880064a7f0b0 > RIP: bdi_put+0x8b/0x1d0 mm/backing-dev.c:914 RSP: ffff880064a7f0b0 > ---[ end trace 8991b3d16ac9bf93 ]--- > > On commit e5d56efc97f8240d0b5d66c03949382b6d7e5570. I also wee the following WARNING. Do you think it' the same underlying bug? ------------[ cut here ]------------ WARNING: CPU: 1 PID: 24265 at mm/backing-dev.c:899 bdi_exit+0x13e/0x160 mm/backing-dev.c:899 Kernel panic - not syncing: panic_on_warn set ... CPU: 1 PID: 24265 Comm: syz-executor3 Not tainted 4.10.0-next-20170227+ #1 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:15 [inline] dump_stack+0x2ee/0x3ef lib/dump_stack.c:51 panic+0x1fb/0x412 kernel/panic.c:179 __warn+0x1c4/0x1e0 kernel/panic.c:540 warn_slowpath_null+0x2c/0x40 kernel/panic.c:583 bdi_exit+0x13e/0x160 mm/backing-dev.c:899 release_bdi+0x19/0x30 mm/backing-dev.c:908 kref_put include/linux/kref.h:72 [inline] bdi_put+0x2a/0x40 mm/backing-dev.c:914 bdev_evict_inode+0x203/0x3a0 fs/block_dev.c:888 evict+0x46e/0x980 fs/inode.c:553 iput_final fs/inode.c:1515 [inline] iput+0x589/0xb20 fs/inode.c:1542 dentry_unlink_inode+0x43b/0x600 fs/dcache.c:343 __dentry_kill+0x34d/0x740 fs/dcache.c:538 dentry_kill fs/dcache.c:579 [inline] dput.part.27+0x5ce/0x7c0 fs/dcache.c:791 dput fs/dcache.c:753 [inline] do_one_tree+0x43/0x50 fs/dcache.c:1454 shrink_dcache_for_umount+0xbb/0x2b0 fs/dcache.c:1468 generic_shutdown_super+0xcd/0x4c0 fs/super.c:421 kill_anon_super+0x3c/0x50 fs/super.c:988 deactivate_locked_super+0x88/0xd0 fs/super.c:309 deactivate_super+0x155/0x1b0 fs/super.c:340 cleanup_mnt+0xb2/0x160 fs/namespace.c:1112 __cleanup_mnt+0x16/0x20 fs/namespace.c:1119 task_work_run+0x18a/0x260 kernel/task_work.c:116 tracehook_notify_resume include/linux/tracehook.h:191 [inline] exit_to_usermode_loop+0x23b/0x2a0 arch/x86/entry/common.c:160 prepare_exit_to_usermode arch/x86/entry/common.c:190 [inline] syscall_return_slowpath+0x4d3/0x570 arch/x86/entry/common.c:259 entry_SYSCALL_64_fastpath+0xc0/0xc2 RIP: 0033:0x44fb79 RSP: 002b:00007fd57a8a0b58 EFLAGS: 00000212 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffea RBX: 0000000000708000 RCX: 000000000044fb79 RDX: 00000000208cf000 RSI: 0000000020058ffd RDI: 0000000020fc2000 RBP: 00000000000002f7 R08: 0000000020691000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000212 R12: 0000000020fc2000 R13: 0000000020058ffd R14: 00000000208cf000 R15: 0000000000000000 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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