by Aleksandr Nogikh

[permalink] [raw]

Subject: Re: [syzbot] BUG: sleeping function called from invalid context in vm_area_dup

On Sat, Oct 22, 2022 at 3:08 AM Tetsuo Handa
<[email protected]> wrote:
>
> On 2022/10/22 13:55, Aleksandr Nogikh wrote:
> > It worked for me:
> >
> > wget 'https://storage.googleapis.com/syzbot-assets/98cc5896cded/disk-acee3e83.raw.xz'
> > unxz disk-acee3e83.raw.xz
> > qemu-system-x86_64 -smp 2,sockets=2,cores=1 -m 4G -drive file=disk-acee3e83.raw,format=raw -snapshot -nographic -enable-kvm
>
> Thanks for command line example.
>
> I tried to add -append option in order to disable modules which cause lockdep splat, but failed
> due to missing -kernel option. Then, I tried to pass downloaded vmlinux to -kernel option in order
> to be able to use -append option, but failed again due to file format difference.
>
> Downloadable vmlinux might be useful for calculating symbol addresses, but downloadable vmlinuz
> would be more helpful for passing to boot loader (with modified kernel command line options).

That's a very good point, thanks!
I've pushed a PR that should make syzbot also upload the kernel image
file (https://github.com/google/syzkaller/pull/3462).

For now, should you still need such file, you can extract it from the
attached bootable image (it's in one of the first partitions).
>
> Anyway, already fixed by commit b232a629b70cccb65d0c in linux-next-20221021.
>
> #syz fix: mm/ksm: convert break_ksm() to use walk_page_range_vma()
>
> [ 43.563343]
> [ 43.564256] ======================================================
> [ 43.565865] WARNING: possible circular locking dependency detected
> [ 43.567533] 6.1.0-rc1-next-20221021+ #2 Not tainted
> [ 43.568874] ------------------------------------------------------
> [ 43.571009] a.out/853 is trying to acquire lock:
> [ 43.572628] ffffffffa72c0b20 (fs_reclaim){+.+.}-{0:0}, at: kmem_cache_alloc+0x46/0x2b0
> [ 43.574677]
> [ 43.574677] but task is already holding lock:
> [ 43.576837] ffff889d041e3498 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: break_ksm_pmd_entry+0xf8/0x290
> [ 43.579093]
> [ 43.579093] which lock already depends on the new lock.
> [ 43.579093]
> [ 43.582819]
> [ 43.582819] the existing dependency chain (in reverse order) is:
> [ 43.585488]
> [ 43.585488] -> #2 (ptlock_ptr(page)#2){+.+.}-{2:2}:
> [ 43.587988] _raw_spin_lock+0x39/0x90
> [ 43.589391] page_vma_mapped_walk+0x737/0xa80
> [ 43.590934] page_vma_mkclean_one.constprop.0+0xf3/0x240
> [ 43.592609] page_mkclean_one+0x94/0xe0
> [ 43.594110] rmap_walk_file+0xf5/0x360
> [ 43.595560] folio_mkclean+0xb3/0xf0
> [ 43.597006] folio_clear_dirty_for_io+0x60/0x2b0
> [ 43.598681] clear_page_dirty_for_io+0x18/0x60
> [ 43.600626] mpage_submit_page+0x24/0x90
> [ 43.602020] mpage_process_page_bufs+0x16c/0x190
> [ 43.603635] mpage_prepare_extent_to_map+0x240/0x4f0
> [ 43.605437] ext4_writepages+0x3cf/0x1400
> [ 43.606957] do_writepages+0xd6/0x1f0
> [ 43.608400] filemap_fdatawrite_wbc+0x75/0xb0
> [ 43.609942] __filemap_fdatawrite_range+0x54/0x80
> [ 43.611580] file_write_and_wait_range+0x53/0xc0
> [ 43.613146] ext4_sync_file+0x135/0x480
> [ 43.614603] vfs_fsync_range+0x49/0xa0
> [ 43.615996] __x64_sys_fsync+0x38/0x80
> [ 43.617405] do_syscall_64+0x5c/0xa0
> [ 43.618758] entry_SYSCALL_64_after_hwframe+0x72/0xdc
> [ 43.620390]
> [ 43.620390] -> #1 (&mapping->i_mmap_rwsem){++++}-{3:3}:
> [ 43.622828] down_write+0x46/0x120
> [ 43.624209] dma_resv_lockdep+0x1d3/0x2cc
> [ 43.625681] do_one_initcall+0x62/0x350
> [ 43.627076] kernel_init_freeable+0x2ec/0x364
> [ 43.628517] kernel_init+0x1b/0x170
> [ 43.629846] ret_from_fork+0x2c/0x50
> [ 43.631195]
> [ 43.631195] -> #0 (fs_reclaim){+.+.}-{0:0}:
> [ 43.633265] __lock_acquire+0x1300/0x2200
> [ 43.634630] lock_acquire+0xd6/0x320
> [ 43.635920] fs_reclaim_acquire+0xaa/0xf0
> [ 43.637324] kmem_cache_alloc+0x46/0x2b0
> [ 43.638762] vm_area_dup+0x25/0xa0
> [ 43.640067] copy_vma+0x102/0x270
> [ 43.641271] move_vma+0x147/0x4d0
> [ 43.642509] __do_sys_mremap+0x206/0x970
> [ 43.643826] __x64_sys_mremap+0x25/0x40
> [ 43.645106] do_syscall_64+0x5c/0xa0
> [ 43.646367] entry_SYSCALL_64_after_hwframe+0x72/0xdc
> [ 43.647894]
> [ 43.647894] other info that might help us debug this:
> [ 43.647894]
> [ 43.650937] Chain exists of:
> [ 43.650937] fs_reclaim --> &mapping->i_mmap_rwsem --> ptlock_ptr(page)#2
> [ 43.650937]
> [ 43.650953] Possible unsafe locking scenario:
> [ 43.650953]
> [ 43.650955] CPU0 CPU1
> [ 43.650956] ---- ----
> [ 43.650958] lock(ptlock_ptr(page)#2);
> [ 43.650965] lock(&mapping->i_mmap_rwsem);
> [ 43.661146] lock(ptlock_ptr(page)#2);
> [ 43.662821] lock(fs_reclaim);
> [ 43.663892]
> [ 43.663892] *** DEADLOCK ***
> [ 43.663892]
> [ 43.666474] 2 locks held by a.out/853:
> [ 43.667641] #0: ffff889d062d1730 (&mm->mmap_lock#2){++++}-{3:3}, at: __do_sys_mremap+0xfe/0x970
> [ 43.669803] #1: ffff889d041e3498 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: break_ksm_pmd_entry+0xf8/0x290
> [ 43.672539]
> [ 43.672539] stack backtrace:
> [ 43.674396] CPU: 3 PID: 853 Comm: a.out Not tainted 6.1.0-rc1-next-20221021+ #2
> [ 43.676232] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
> [ 43.678257] Call Trace:
> [ 43.679255] <TASK>
> [ 43.680192] dump_stack_lvl+0x5a/0x88
> [ 43.681416] find_cpio_data.cold-0x6/0x5b
> [ 43.682714] print_shortest_lock_dependencies.cold-0x5/0x8d
> [ 43.684297] check_noncircular+0x103/0x130
> [ 43.685630] __lock_acquire+0x1300/0x2200
> [ 43.686973] lock_acquire+0xd6/0x320
> [ 43.688182] ? kmem_cache_alloc+0x46/0x2b0
> [ 43.689489] ? __lock_acquire+0x3e1/0x2200
> [ 43.691049] fs_reclaim_acquire+0xaa/0xf0
> [ 43.692395] ? kmem_cache_alloc+0x46/0x2b0
> [ 43.693760] kmem_cache_alloc+0x46/0x2b0
> [ 43.695117] ? vm_area_dup+0x25/0xa0
> [ 43.696337] vm_area_dup+0x25/0xa0
> [ 43.697570] ? sched_clock+0x9/0x20
> [ 43.698812] ? __memcpy-0xd/0x30
> [ 43.699955] ? lock_release+0x14e/0x4b0
> [ 43.701206] ? mt_find+0x179/0x660
> [ 43.702346] ? vma_merge+0x232/0x340
> [ 43.703597] ? copy_vma+0xa0/0x270
> [ 43.704748] copy_vma+0x102/0x270
> [ 43.705956] move_vma+0x147/0x4d0
> [ 43.707157] ? thp_get_unmapped_area+0xca/0xf0
> [ 43.708528] __do_sys_mremap+0x206/0x970
> [ 43.709786] ? syscall_enter_from_user_mode+0x21/0x70
> [ 43.711208] ? __memcpy-0xd/0x30
> [ 43.712369] ? lockdep_hardirqs_on+0x86/0x120
> [ 43.713722] __x64_sys_mremap+0x25/0x40
> [ 43.715013] do_syscall_64+0x5c/0xa0
> [ 43.716269] ? syscall_exit_to_user_mode+0x37/0x60
> [ 43.717682] ? do_syscall_64+0x69/0xa0
> [ 43.718826] entry_SYSCALL_64_after_hwframe+0x72/0xdc
> [ 43.720245] RIP: 0033:0x447e8d
> [ 43.721412] Code: 28 c3 e8 46 1e 00 00 66 0f 1f 44 00 00 f3 0f 1e fa 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 b8 ff ff ff f7 d8 64 89 01 48
> [ 43.726518] RSP: 002b:00007fffb8598528 EFLAGS: 00000246 ORIG_RAX: 0000000000000019
> [ 43.728446] RAX: ffffffffffffffda RBX: 00007fffb8598738 RCX: 0000000000447e8d
> [ 43.730346] RDX: 0000000000001000 RSI: 0000000000004000 RDI: 00000000201c4000
> [ 43.732299] RBP: 0000000000000001 R08: 00000000202ef000 R09: 0000000000000000
> [ 43.734174] R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000001
> [ 43.735999] R13: 00007fffb8598728 R14: 00000000004c17d0 R15: 0000000000000001
> [ 43.737958] </TASK>
> [ 43.739102] BUG: sleeping function called from invalid context at include/linux/sched/mm.h:274
> [ 43.741273] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 853, name: a.out
> [ 43.743400] preempt_count: 1, expected: 0
> [ 43.744780] RCU nest depth: 0, expected: 0
> [ 43.746249] INFO: lockdep is turned off.
> [ 43.747628] Preemption disabled at:
> [ 43.747631] [<ffffffffa5c04158>] break_ksm_pmd_entry+0xf8/0x290
> [ 43.750708] CPU: 3 PID: 853 Comm: a.out Not tainted 6.1.0-rc1-next-20221021+ #2
> [ 43.752741] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
> [ 43.754964] Call Trace:
> [ 43.756143] <TASK>
> [ 43.757235] dump_stack_lvl+0x5a/0x88
> [ 43.758628] find_cpio_data.cold-0x6/0x5b
> [ 43.760044] __might_resched.cold+0x13c/0x162
> [ 43.761536] __might_sleep+0x50/0xa0
> [ 43.762967] kmem_cache_alloc+0x265/0x2b0
> [ 43.764408] ? vm_area_dup+0x25/0xa0
> [ 43.765785] vm_area_dup+0x25/0xa0
> [ 43.767175] ? sched_clock+0x9/0x20
> [ 43.768530] ? __memcpy-0xd/0x30
> [ 43.769802] ? lock_release+0x14e/0x4b0
> [ 43.771288] ? mt_find+0x179/0x660
> [ 43.772931] ? vma_merge+0x232/0x340
> [ 43.774290] ? copy_vma+0xa0/0x270
> [ 43.775603] copy_vma+0x102/0x270
> [ 43.776899] move_vma+0x147/0x4d0
> [ 43.778168] ? thp_get_unmapped_area+0xca/0xf0
> [ 43.779641] __do_sys_mremap+0x206/0x970
> [ 43.780984] ? syscall_enter_from_user_mode+0x21/0x70
> [ 43.782511] ? __memcpy-0xd/0x30
> [ 43.783682] ? lockdep_hardirqs_on+0x86/0x120
> [ 43.785057] __x64_sys_mremap+0x25/0x40
> [ 43.786346] do_syscall_64+0x5c/0xa0
> [ 43.787603] ? syscall_exit_to_user_mode+0x37/0x60
> [ 43.789037] ? do_syscall_64+0x69/0xa0
> [ 43.790337] entry_SYSCALL_64_after_hwframe+0x72/0xdc
> [ 43.791934] RIP: 0033:0x447e8d
> [ 43.793053] Code: 28 c3 e8 46 1e 00 00 66 0f 1f 44 00 00 f3 0f 1e fa 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 b8 ff ff ff f7 d8 64 89 01 48
> [ 43.798111] RSP: 002b:00007fffb8598528 EFLAGS: 00000246 ORIG_RAX: 0000000000000019
> [ 43.800098] RAX: ffffffffffffffda RBX: 00007fffb8598738 RCX: 0000000000447e8d
> [ 43.802002] RDX: 0000000000001000 RSI: 0000000000004000 RDI: 00000000201c4000
> [ 43.803916] RBP: 0000000000000001 R08: 00000000202ef000 R09: 0000000000000000
> [ 43.805887] R10: 0000000000000003 R11: 0000000000000246 R12: 0000000000000001
> [ 43.807773] R13: 00007fffb8598728 R14: 00000000004c17d0 R15: 0000000000000001
> [ 43.809648] </TASK>
>
>
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