possible deadlock in shmem_mfill_atomic_pte

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 527630fb Merge tag 'clk-fixes-for-linus' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1214875be00000
kernel config: https://syzkaller.appspot.com/x/.config?x=27392dd2975fd692
dashboard link: https://syzkaller.appspot.com/bug?extid=e27980339d305f2dbfd9
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

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

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e27980...@syzkaller.appspotmail.com

WARNING: possible irq lock inversion dependency detected
5.6.0-rc7-syzkaller #0 Not tainted
--------------------------------------------------------
syz-executor.0/10317 just changed the state of lock:
ffff888021d16568 (&(&info->lock)->rlock){+.+.}, at: spin_lock include/linux/spinlock.h:338 [inline]
ffff888021d16568 (&(&info->lock)->rlock){+.+.}, at: shmem_mfill_atomic_pte+0x1012/0x21c0 mm/shmem.c:2407
but this lock was taken by another, SOFTIRQ-safe lock in the past:
(&(&xa->xa_lock)->rlock#5){..-.}


and interrupts could create inverse lock ordering between them.


other info that might help us debug this:
Possible interrupt unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&(&info->lock)->rlock);
local_irq_disable();
lock(&(&xa->xa_lock)->rlock#5);
lock(&(&info->lock)->rlock);
<Interrupt>
lock(&(&xa->xa_lock)->rlock#5);

*** DEADLOCK ***

2 locks held by syz-executor.0/10317:
#0: ffff888011721898 (&mm->mmap_sem#2){++++}, at: __mcopy_atomic mm/userfaultfd.c:474 [inline]
#0: ffff888011721898 (&mm->mmap_sem#2){++++}, at: mcopy_atomic+0x185/0x2510 mm/userfaultfd.c:607
#1: ffff888024eda280 (&(ptlock_ptr(page))->rlock#2){+.+.}, at: spin_lock include/linux/spinlock.h:338 [inline]
#1: ffff888024eda280 (&(ptlock_ptr(page))->rlock#2){+.+.}, at: shmem_mfill_atomic_pte+0xf76/0x21c0 mm/shmem.c:2394

the shortest dependencies between 2nd lock and 1st lock:
-> (&(&xa->xa_lock)->rlock#5){..-.} {
IN-SOFTIRQ-W at:
lock_acquire+0x197/0x420 kernel/locking/lockdep.c:4484
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x8c/0xbf kernel/locking/spinlock.c:159
test_clear_page_writeback+0x1d7/0x11e0 mm/page-writeback.c:2728
end_page_writeback+0x239/0x520 mm/filemap.c:1317
end_buffer_async_write+0x6a9/0xa30 fs/buffer.c:389
end_bio_bh_io_sync+0xe2/0x140 fs/buffer.c:3018
bio_endio+0x473/0x820 block/bio.c:1872
req_bio_endio block/blk-core.c:245 [inline]
blk_update_request+0x3e1/0xdc0 block/blk-core.c:1468
scsi_end_request+0x80/0x7a0 drivers/scsi/scsi_lib.c:576
scsi_io_completion+0x1e7/0x1300 drivers/scsi/scsi_lib.c:960
scsi_softirq_done+0x31e/0x3b0 drivers/scsi/scsi_lib.c:1476
blk_done_softirq+0x2db/0x440 block/blk-softirq.c:37
__do_softirq+0x26c/0x99d kernel/softirq.c:292
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0x192/0x1d0 kernel/softirq.c:413
exiting_irq arch/x86/include/asm/apic.h:546 [inline]
do_IRQ+0xde/0x280 arch/x86/kernel/irq.c:263
ret_from_intr+0x0/0x36
clear_page_erms+0x7/0x10 arch/x86/lib/clear_page_64.S:48
clear_page arch/x86/include/asm/page_64.h:49 [inline]
clear_highpage include/linux/highmem.h:214 [inline]
kernel_init_free_pages+0x92/0x120 mm/page_alloc.c:1118
prep_new_page+0x12e/0x1f0 mm/page_alloc.c:2160
get_page_from_freelist+0x14c7/0x3ee0 mm/page_alloc.c:3684
__alloc_pages_nodemask+0x2a5/0x820 mm/page_alloc.c:4731
alloc_pages_current+0xff/0x200 mm/mempolicy.c:2211
alloc_pages include/linux/gfp.h:532 [inline]
__page_cache_alloc+0x298/0x480 mm/filemap.c:959
__do_page_cache_readahead+0x1a7/0x570 mm/readahead.c:196
ra_submit mm/internal.h:62 [inline]
ondemand_readahead+0x566/0xd60 mm/readahead.c:492
page_cache_async_readahead mm/readahead.c:574 [inline]
page_cache_async_readahead+0x43d/0x7c0 mm/readahead.c:547
generic_file_buffered_read mm/filemap.c:2037 [inline]
generic_file_read_iter+0x124a/0x2b00 mm/filemap.c:2302
ext4_file_read_iter fs/ext4/file.c:131 [inline]
ext4_file_read_iter+0x1d1/0x600 fs/ext4/file.c:114
call_read_iter include/linux/fs.h:1896 [inline]
new_sync_read+0x4a2/0x790 fs/read_write.c:414
__vfs_read+0xc9/0x100 fs/read_write.c:427
integrity_kernel_read+0x143/0x200 security/integrity/iint.c:200
ima_calc_file_hash_tfm+0x2aa/0x3b0 security/integrity/ima/ima_crypto.c:360
ima_calc_file_shash security/integrity/ima/ima_crypto.c:391 [inline]
ima_calc_file_hash+0x199/0x540 security/integrity/ima/ima_crypto.c:456
ima_collect_measurement+0x4c4/0x570 security/integrity/ima/ima_api.c:249
process_measurement+0xc6d/0x1740 security/integrity/ima/ima_main.c:326
ima_bprm_check+0xde/0x210 security/integrity/ima/ima_main.c:417
security_bprm_check+0x89/0xb0 security/security.c:819
search_binary_handler+0x70/0x580 fs/exec.c:1649
exec_binprm fs/exec.c:1705 [inline]
__do_execve_file.isra.0+0x12fc/0x2270 fs/exec.c:1825
do_execveat_common fs/exec.c:1871 [inline]
do_execve fs/exec.c:1888 [inline]
__do_sys_execve fs/exec.c:1964 [inline]
__se_sys_execve fs/exec.c:1959 [inline]
__x64_sys_execve+0x8a/0xb0 fs/exec.c:1959
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
INITIAL USE at:
lock_acquire+0x197/0x420 kernel/locking/lockdep.c:4484
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x5b/0x80 kernel/locking/spinlock.c:167
spin_lock_irq include/linux/spinlock.h:363 [inline]
clear_inode+0x1b/0x1e0 fs/inode.c:529
shmem_evict_inode+0x1db/0x9f0 mm/shmem.c:1116
evict+0x2ed/0x650 fs/inode.c:576
iput_final fs/inode.c:1572 [inline]
iput+0x536/0x8c0 fs/inode.c:1598
dentry_unlink_inode+0x2c0/0x3e0 fs/dcache.c:374
d_delete fs/dcache.c:2451 [inline]
d_delete+0x117/0x150 fs/dcache.c:2440
vfs_unlink+0x4d5/0x620 fs/namei.c:4087
handle_remove+0x417/0x720 drivers/base/devtmpfs.c:332
handle drivers/base/devtmpfs.c:378 [inline]
devtmpfsd.part.0+0x302/0x750 drivers/base/devtmpfs.c:413
devtmpfsd+0x107/0x120 drivers/base/devtmpfs.c:403
kthread+0x357/0x430 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
}
... key at: [<ffffffff8c402aa0>] __key.17910+0x0/0x40
... acquired at:
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x8c/0xbf kernel/locking/spinlock.c:159
shmem_uncharge+0x24/0x270 mm/shmem.c:341
__split_huge_page mm/huge_memory.c:2540 [inline]
split_huge_page_to_list+0x2751/0x33c0 mm/huge_memory.c:2813
split_huge_page include/linux/huge_mm.h:169 [inline]
shmem_unused_huge_shrink+0x7ba/0x13a0 mm/shmem.c:542
shmem_unused_huge_scan+0x7a/0xb0 mm/shmem.c:574
super_cache_scan+0x34f/0x480 fs/super.c:111
do_shrink_slab+0x3fc/0xab0 mm/vmscan.c:512
shrink_slab mm/vmscan.c:673 [inline]
shrink_slab+0x16f/0x5f0 mm/vmscan.c:646
shrink_node_memcgs mm/vmscan.c:2676 [inline]
shrink_node+0x477/0x1b20 mm/vmscan.c:2780
shrink_zones mm/vmscan.c:2983 [inline]
do_try_to_free_pages+0x38d/0x13a0 mm/vmscan.c:3036
try_to_free_pages+0x293/0x8d0 mm/vmscan.c:3275
__perform_reclaim mm/page_alloc.c:4113 [inline]
__alloc_pages_direct_reclaim mm/page_alloc.c:4134 [inline]
__alloc_pages_slowpath+0x919/0x26a0 mm/page_alloc.c:4537
__alloc_pages_nodemask+0x5e1/0x820 mm/page_alloc.c:4751
__alloc_pages include/linux/gfp.h:496 [inline]
__alloc_pages_node include/linux/gfp.h:509 [inline]
alloc_pages_vma+0x3bd/0x600 mm/mempolicy.c:2155
shmem_alloc_hugepage+0x122/0x210 mm/shmem.c:1484
shmem_alloc_and_acct_page+0x3ba/0x980 mm/shmem.c:1522
shmem_getpage_gfp+0xdb9/0x2860 mm/shmem.c:1835
shmem_getpage mm/shmem.c:154 [inline]
shmem_write_begin+0x102/0x1e0 mm/shmem.c:2488
generic_perform_write+0x20a/0x4e0 mm/filemap.c:3287
__generic_file_write_iter+0x24c/0x610 mm/filemap.c:3416
generic_file_write_iter+0x3f0/0x62d mm/filemap.c:3448
call_write_iter include/linux/fs.h:1902 [inline]
new_sync_write+0x49c/0x700 fs/read_write.c:483
__vfs_write+0xc9/0x100 fs/read_write.c:496
vfs_write+0x262/0x5c0 fs/read_write.c:558
ksys_write+0x127/0x250 fs/read_write.c:611
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe

-> (&(&info->lock)->rlock){+.+.} {
HARDIRQ-ON-W at:
lock_acquire+0x197/0x420 kernel/locking/lockdep.c:4484
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:338 [inline]
shmem_mfill_atomic_pte+0x1012/0x21c0 mm/shmem.c:2407
shmem_mcopy_atomic_pte+0x3a/0x50 mm/shmem.c:2445
mfill_atomic_pte mm/userfaultfd.c:434 [inline]
__mcopy_atomic mm/userfaultfd.c:557 [inline]
mcopy_atomic+0xac7/0x2510 mm/userfaultfd.c:607
userfaultfd_copy fs/userfaultfd.c:1736 [inline]
userfaultfd_ioctl+0x4d2/0x3b10 fs/userfaultfd.c:1886
vfs_ioctl fs/ioctl.c:47 [inline]
ksys_ioctl+0x11a/0x180 fs/ioctl.c:763
__do_sys_ioctl fs/ioctl.c:772 [inline]
__se_sys_ioctl fs/ioctl.c:770 [inline]
__x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
SOFTIRQ-ON-W at:
lock_acquire+0x197/0x420 kernel/locking/lockdep.c:4484
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:338 [inline]
shmem_mfill_atomic_pte+0x1012/0x21c0 mm/shmem.c:2407
shmem_mcopy_atomic_pte+0x3a/0x50 mm/shmem.c:2445
mfill_atomic_pte mm/userfaultfd.c:434 [inline]
__mcopy_atomic mm/userfaultfd.c:557 [inline]
mcopy_atomic+0xac7/0x2510 mm/userfaultfd.c:607
userfaultfd_copy fs/userfaultfd.c:1736 [inline]
userfaultfd_ioctl+0x4d2/0x3b10 fs/userfaultfd.c:1886
vfs_ioctl fs/ioctl.c:47 [inline]
ksys_ioctl+0x11a/0x180 fs/ioctl.c:763
__do_sys_ioctl fs/ioctl.c:772 [inline]
__se_sys_ioctl fs/ioctl.c:770 [inline]
__x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
INITIAL USE at:
lock_acquire+0x197/0x420 kernel/locking/lockdep.c:4484
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x5b/0x80 kernel/locking/spinlock.c:167
spin_lock_irq include/linux/spinlock.h:363 [inline]
shmem_getpage_gfp+0xf10/0x2860 mm/shmem.c:1887
shmem_read_mapping_page_gfp+0xd3/0x170 mm/shmem.c:4218
shmem_read_mapping_page include/linux/shmem_fs.h:101 [inline]
drm_gem_get_pages+0x293/0x530 drivers/gpu/drm/drm_gem.c:578
drm_gem_shmem_get_pages_locked drivers/gpu/drm/drm_gem_shmem_helper.c:146 [inline]
drm_gem_shmem_get_pages+0x9d/0x160 drivers/gpu/drm/drm_gem_shmem_helper.c:175
virtio_gpu_object_attach+0x121/0x950 drivers/gpu/drm/virtio/virtgpu_vq.c:1090
virtio_gpu_object_create+0x26f/0x490 drivers/gpu/drm/virtio/virtgpu_object.c:150
virtio_gpu_gem_create+0xaa/0x1d0 drivers/gpu/drm/virtio/virtgpu_gem.c:42
virtio_gpu_mode_dumb_create+0x21e/0x360 drivers/gpu/drm/virtio/virtgpu_gem.c:82
drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94
drm_client_buffer_create drivers/gpu/drm/drm_client.c:267 [inline]
drm_client_framebuffer_create+0x1b7/0x770 drivers/gpu/drm/drm_client.c:412
drm_fb_helper_generic_probe+0x1e4/0x810 drivers/gpu/drm/drm_fb_helper.c:2051
drm_fb_helper_single_fb_probe drivers/gpu/drm/drm_fb_helper.c:1600 [inline]
__drm_fb_helper_initial_config_and_unlock+0xb56/0x11e0 drivers/gpu/drm/drm_fb_helper.c:1758
drm_fb_helper_initial_config drivers/gpu/drm/drm_fb_helper.c:1853 [inline]
drm_fb_helper_initial_config drivers/gpu/drm/drm_fb_helper.c:1845 [inline]
drm_fbdev_client_hotplug+0x30f/0x580 drivers/gpu/drm/drm_fb_helper.c:2145
drm_fbdev_generic_setup drivers/gpu/drm/drm_fb_helper.c:2224 [inline]
drm_fbdev_generic_setup+0x18b/0x295 drivers/gpu/drm/drm_fb_helper.c:2197
virtio_gpu_probe+0x28f/0x2de drivers/gpu/drm/virtio/virtgpu_drv.c:126
virtio_dev_probe+0x463/0x710 drivers/virtio/virtio.c:248
really_probe+0x281/0x6d0 drivers/base/dd.c:551
driver_probe_device+0x104/0x210 drivers/base/dd.c:724
device_driver_attach+0x108/0x140 drivers/base/dd.c:998
__driver_attach+0xda/0x240 drivers/base/dd.c:1075
bus_for_each_dev+0x14b/0x1d0 drivers/base/bus.c:305
bus_add_driver+0x4a2/0x5a0 drivers/base/bus.c:622
driver_register+0x1c4/0x330 drivers/base/driver.c:171
do_one_initcall+0x10a/0x7d0 init/main.c:1152
do_initcall_level init/main.c:1225 [inline]
do_initcalls init/main.c:1241 [inline]
do_basic_setup init/main.c:1261 [inline]
kernel_init_freeable+0x501/0x5ae init/main.c:1445
kernel_init+0xd/0x1bb init/main.c:1352
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
}
... key at: [<ffffffff8c3f0420>] __key.55978+0x0/0x40
... acquired at:
mark_lock_irq kernel/locking/lockdep.c:3316 [inline]
mark_lock+0x50e/0x1220 kernel/locking/lockdep.c:3665
mark_usage kernel/locking/lockdep.c:3583 [inline]
__lock_acquire+0x1236/0x3ca0 kernel/locking/lockdep.c:3908
lock_acquire+0x197/0x420 kernel/locking/lockdep.c:4484
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:338 [inline]
shmem_mfill_atomic_pte+0x1012/0x21c0 mm/shmem.c:2407
shmem_mcopy_atomic_pte+0x3a/0x50 mm/shmem.c:2445
mfill_atomic_pte mm/userfaultfd.c:434 [inline]
__mcopy_atomic mm/userfaultfd.c:557 [inline]
mcopy_atomic+0xac7/0x2510 mm/userfaultfd.c:607
userfaultfd_copy fs/userfaultfd.c:1736 [inline]
userfaultfd_ioctl+0x4d2/0x3b10 fs/userfaultfd.c:1886
vfs_ioctl fs/ioctl.c:47 [inline]
ksys_ioctl+0x11a/0x180 fs/ioctl.c:763
__do_sys_ioctl fs/ioctl.c:772 [inline]
__se_sys_ioctl fs/ioctl.c:770 [inline]
__x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe


stack backtrace:
CPU: 0 PID: 10317 Comm: syz-executor.0 Not tainted 5.6.0-rc7-syzkaller #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu.org 04/01/2014
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x188/0x20d lib/dump_stack.c:118
print_irq_inversion_bug kernel/locking/lockdep.c:3179 [inline]
check_usage_backwards.cold+0x1d/0x26 kernel/locking/lockdep.c:3230
mark_lock_irq kernel/locking/lockdep.c:3316 [inline]
mark_lock+0x50e/0x1220 kernel/locking/lockdep.c:3665
mark_usage kernel/locking/lockdep.c:3583 [inline]
__lock_acquire+0x1236/0x3ca0 kernel/locking/lockdep.c:3908
lock_acquire+0x197/0x420 kernel/locking/lockdep.c:4484
__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151
spin_lock include/linux/spinlock.h:338 [inline]
shmem_mfill_atomic_pte+0x1012/0x21c0 mm/shmem.c:2407
shmem_mcopy_atomic_pte+0x3a/0x50 mm/shmem.c:2445
mfill_atomic_pte mm/userfaultfd.c:434 [inline]
__mcopy_atomic mm/userfaultfd.c:557 [inline]
mcopy_atomic+0xac7/0x2510 mm/userfaultfd.c:607
userfaultfd_copy fs/userfaultfd.c:1736 [inline]
userfaultfd_ioctl+0x4d2/0x3b10 fs/userfaultfd.c:1886
vfs_ioctl fs/ioctl.c:47 [inline]
ksys_ioctl+0x11a/0x180 fs/ioctl.c:763
__do_sys_ioctl fs/ioctl.c:772 [inline]
__se_sys_ioctl fs/ioctl.c:770 [inline]
__x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:770
do_syscall_64+0xf6/0x7d0 arch/x86/entry/common.c:294
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c6e9
Code: bd b1 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 8b b1 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fcff1e50c88 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000072bf00 RCX: 000000000045c6e9
RDX: 00000000200a0fe0 RSI: 00000000c028aa03 RDI: 0000000000000003
RBP: 00007fcff1e516d4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000005b3 R14: 00000000004af2cd R15: 00000000006ec420


---
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[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit: ab6f762f printk: queue wake_up_klogd irq_work only if per-..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=158a6b5de00000
kernel config: https://syzkaller.appspot.com/x/.config?x=3010ccb0f380f660
dashboard link: https://syzkaller.appspot.com/bug?extid=e27980339d305f2dbfd9
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12d3c5afe00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15e7f51be00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e27980...@syzkaller.appspotmail.com

========================================================

WARNING: possible irq lock inversion dependency detected

5.6.0-syzkaller #0 Not tainted
--------------------------------------------------------
syz-executor941/7000 just changed the state of lock:
ffff88808d9b18d8 (&info->lock){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:353 [inline]
ffff88808d9b18d8 (&info->lock){+.+.}-{2:2}, at: shmem_mfill_atomic_pte+0x13f4/0x1e10 mm/shmem.c:2402

but this lock was taken by another, SOFTIRQ-safe lock in the past:

(&xa->xa_lock#4){..-.}-{2:2}

and interrupts could create inverse lock ordering between them.


other info that might help us debug this:
Possible interrupt unsafe locking scenario:

CPU0 CPU1
---- ----

lock(&info->lock);
local_irq_disable();
lock(&xa->xa_lock#4);
lock(&info->lock);
<Interrupt>
lock(&xa->xa_lock#4);

*** DEADLOCK ***

2 locks held by syz-executor941/7000:
#0: ffff88809edf10e8 (&mm->mmap_sem#2){++++}-{3:3}, at: __mcopy_atomic mm/userfaultfd.c:491 [inline]
#0: ffff88809edf10e8 (&mm->mmap_sem#2){++++}-{3:3}, at: mcopy_atomic+0x17a/0x1ba0 mm/userfaultfd.c:632
#1: ffff888098e211f8 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: spin_lock include/linux/spinlock.h:353 [inline]
#1: ffff888098e211f8 (ptlock_ptr(page)#2){+.+.}-{2:2}, at: shmem_mfill_atomic_pte+0xf73/0x1e10 mm/shmem.c:2389

the shortest dependencies between 2nd lock and 1st lock:

-> (&xa->xa_lock#4){..-.}-{2:2} {
IN-SOFTIRQ-W at:
lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x9e/0xc0 kernel/locking/spinlock.c:159
test_clear_page_writeback+0x2d8/0xac0 mm/page-writeback.c:2728
end_page_writeback+0x212/0x390 mm/filemap.c:1317
end_bio_bh_io_sync+0xb1/0x110 fs/buffer.c:3012
req_bio_endio block/blk-core.c:245 [inline]
blk_update_request+0x437/0x1070 block/blk-core.c:1472
scsi_end_request+0x7a/0x7f0 drivers/scsi/scsi_lib.c:575
scsi_io_completion+0x178/0x1be0 drivers/scsi/scsi_lib.c:959
blk_done_softirq+0x2f2/0x360 block/blk-softirq.c:37
__do_softirq+0x268/0x80c kernel/softirq.c:292
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0x223/0x230 kernel/softirq.c:413
exiting_irq arch/x86/include/asm/apic.h:546 [inline]
do_IRQ+0xfb/0x1d0 arch/x86/kernel/irq.c:263
ret_from_intr+0x0/0x2b
orc_find arch/x86/kernel/unwind_orc.c:164 [inline]
unwind_next_frame+0x20b/0x1cf0 arch/x86/kernel/unwind_orc.c:407
arch_stack_walk+0xb4/0xe0 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0xad/0x150 kernel/stacktrace.c:123
save_stack mm/kasan/common.c:49 [inline]
set_track mm/kasan/common.c:57 [inline]
__kasan_kmalloc+0x114/0x160 mm/kasan/common.c:495
__do_kmalloc mm/slab.c:3656 [inline]
__kmalloc+0x24b/0x330 mm/slab.c:3665
kmalloc include/linux/slab.h:560 [inline]
tomoyo_realpath_from_path+0xd8/0x630 security/tomoyo/realpath.c:252
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_check_open_permission+0x1b6/0x900 security/tomoyo/file.c:771
security_file_open+0x50/0xc0 security/security.c:1548
do_dentry_open+0x35d/0x10b0 fs/open.c:784
do_open fs/namei.c:3229 [inline]
path_openat+0x2790/0x38b0 fs/namei.c:3346
do_filp_open+0x191/0x3a0 fs/namei.c:3373
do_sys_openat2+0x463/0x770 fs/open.c:1148
do_sys_open fs/open.c:1164 [inline]
ksys_open include/linux/syscalls.h:1386 [inline]
__do_sys_open fs/open.c:1170 [inline]
__se_sys_open fs/open.c:1168 [inline]
__x64_sys_open+0x1af/0x1e0 fs/open.c:1168
do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3
INITIAL USE at:
lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x67/0x80 kernel/locking/spinlock.c:167
spin_lock_irq include/linux/spinlock.h:378 [inline]
__add_to_page_cache_locked+0x53d/0xc70 mm/filemap.c:855
add_to_page_cache_lru+0x17f/0x4d0 mm/filemap.c:921
do_read_cache_page+0x209/0xd00 mm/filemap.c:2755
read_mapping_page include/linux/pagemap.h:397 [inline]
read_part_sector+0xd8/0x2d0 block/partitions/core.c:643
adfspart_check_ICS+0x45/0x640 block/partitions/acorn.c:360
check_partition block/partitions/core.c:140 [inline]
blk_add_partitions+0x3ce/0x1240 block/partitions/core.c:571
bdev_disk_changed+0x446/0x5d0 fs/block_dev.c:1544
__blkdev_get+0xb2b/0x13d0 fs/block_dev.c:1647
register_disk block/genhd.c:763 [inline]
__device_add_disk+0x95f/0x1040 block/genhd.c:853
add_disk include/linux/genhd.h:294 [inline]
brd_init+0x349/0x42a drivers/block/brd.c:533
do_one_initcall+0x14b/0x350 init/main.c:1157
do_initcall_level+0x101/0x14c init/main.c:1230
do_initcalls+0x59/0x9b init/main.c:1246
kernel_init_freeable+0x2fa/0x418 init/main.c:1450
kernel_init+0xd/0x290 init/main.c:1357
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
}
... key at: [<ffffffff8b5afa68>] xa_init_flags.__key+0x0/0x10
... acquired at:
lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923
__raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
_raw_spin_lock_irqsave+0x9e/0xc0 kernel/locking/spinlock.c:159
shmem_uncharge+0x34/0x4c0 mm/shmem.c:341
__split_huge_page+0xda8/0x1900 mm/huge_memory.c:2613
split_huge_page_to_list+0x10a4/0x15f0 mm/huge_memory.c:2886
split_huge_page include/linux/huge_mm.h:204 [inline]
shmem_punch_compound+0x17d/0x1c0 mm/shmem.c:814
shmem_undo_range+0x5da/0x1d00 mm/shmem.c:870
shmem_truncate_range mm/shmem.c:980 [inline]
shmem_setattr+0x4e3/0x8a0 mm/shmem.c:1039
notify_change+0xad5/0xfb0 fs/attr.c:336
do_truncate fs/open.c:64 [inline]
do_sys_ftruncate+0x55f/0x690 fs/open.c:195
do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3

-> (&info->lock){+.+.}-{2:2} {
HARDIRQ-ON-W at:
lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923

__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151

spin_lock include/linux/spinlock.h:353 [inline]
shmem_mfill_atomic_pte+0x13f4/0x1e10 mm/shmem.c:2402
shmem_mcopy_atomic_pte+0x3a/0x50 mm/shmem.c:2440
mfill_atomic_pte mm/userfaultfd.c:449 [inline]
__mcopy_atomic mm/userfaultfd.c:582 [inline]
mcopy_atomic+0x84f/0x1ba0 mm/userfaultfd.c:632
userfaultfd_copy fs/userfaultfd.c:1743 [inline]
userfaultfd_ioctl+0x2289/0x4890 fs/userfaultfd.c:1941
vfs_ioctl fs/ioctl.c:47 [inline]
ksys_ioctl fs/ioctl.c:763 [inline]
__do_sys_ioctl fs/ioctl.c:772 [inline]
__se_sys_ioctl+0xf9/0x160 fs/ioctl.c:770
do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3
SOFTIRQ-ON-W at:
lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923

__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151

spin_lock include/linux/spinlock.h:353 [inline]
shmem_mfill_atomic_pte+0x13f4/0x1e10 mm/shmem.c:2402
shmem_mcopy_atomic_pte+0x3a/0x50 mm/shmem.c:2440
mfill_atomic_pte mm/userfaultfd.c:449 [inline]
__mcopy_atomic mm/userfaultfd.c:582 [inline]
mcopy_atomic+0x84f/0x1ba0 mm/userfaultfd.c:632
userfaultfd_copy fs/userfaultfd.c:1743 [inline]
userfaultfd_ioctl+0x2289/0x4890 fs/userfaultfd.c:1941
vfs_ioctl fs/ioctl.c:47 [inline]
ksys_ioctl fs/ioctl.c:763 [inline]
__do_sys_ioctl fs/ioctl.c:772 [inline]
__se_sys_ioctl+0xf9/0x160 fs/ioctl.c:770
do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3
INITIAL USE at:
lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923
__raw_spin_lock_irq include/linux/spinlock_api_smp.h:128 [inline]
_raw_spin_lock_irq+0x67/0x80 kernel/locking/spinlock.c:167
spin_lock_irq include/linux/spinlock.h:378 [inline]
shmem_getpage_gfp+0x2160/0x3120 mm/shmem.c:1882
shmem_getpage mm/shmem.c:154 [inline]
shmem_write_begin+0xcd/0x1a0 mm/shmem.c:2483
generic_perform_write+0x23b/0x4e0 mm/filemap.c:3302
__generic_file_write_iter+0x22b/0x4e0 mm/filemap.c:3431
generic_file_write_iter+0x4a6/0x650 mm/filemap.c:3463
call_write_iter include/linux/fs.h:1907 [inline]
new_sync_write fs/read_write.c:484 [inline]
__vfs_write+0x54c/0x710 fs/read_write.c:497
vfs_write+0x274/0x580 fs/read_write.c:559
ksys_write+0x11b/0x220 fs/read_write.c:612
do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3
}
... key at: [<ffffffff8b59f840>] shmem_get_inode.__key+0x0/0x10
... acquired at:
mark_lock_irq kernel/locking/lockdep.c:3585 [inline]
mark_lock+0x529/0x1b00 kernel/locking/lockdep.c:3935
mark_usage kernel/locking/lockdep.c:3852 [inline]
__lock_acquire+0xb95/0x2b90 kernel/locking/lockdep.c:4298
lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923

__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151

spin_lock include/linux/spinlock.h:353 [inline]
shmem_mfill_atomic_pte+0x13f4/0x1e10 mm/shmem.c:2402
shmem_mcopy_atomic_pte+0x3a/0x50 mm/shmem.c:2440
mfill_atomic_pte mm/userfaultfd.c:449 [inline]
__mcopy_atomic mm/userfaultfd.c:582 [inline]
mcopy_atomic+0x84f/0x1ba0 mm/userfaultfd.c:632
userfaultfd_copy fs/userfaultfd.c:1743 [inline]
userfaultfd_ioctl+0x2289/0x4890 fs/userfaultfd.c:1941
vfs_ioctl fs/ioctl.c:47 [inline]
ksys_ioctl fs/ioctl.c:763 [inline]
__do_sys_ioctl fs/ioctl.c:772 [inline]
__se_sys_ioctl+0xf9/0x160 fs/ioctl.c:770
do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3


stack backtrace:
CPU: 1 PID: 7000 Comm: syz-executor941 Not tainted 5.6.0-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+0x1e9/0x30e lib/dump_stack.c:118
print_irq_inversion_bug+0xb67/0xe90 kernel/locking/lockdep.c:3447
check_usage_backwards+0x13f/0x240 kernel/locking/lockdep.c:3499
mark_lock_irq kernel/locking/lockdep.c:3585 [inline]
mark_lock+0x529/0x1b00 kernel/locking/lockdep.c:3935
mark_usage kernel/locking/lockdep.c:3852 [inline]
__lock_acquire+0xb95/0x2b90 kernel/locking/lockdep.c:4298
lock_acquire+0x169/0x480 kernel/locking/lockdep.c:4923

__raw_spin_lock include/linux/spinlock_api_smp.h:142 [inline]
_raw_spin_lock+0x2a/0x40 kernel/locking/spinlock.c:151

spin_lock include/linux/spinlock.h:353 [inline]
shmem_mfill_atomic_pte+0x13f4/0x1e10 mm/shmem.c:2402
shmem_mcopy_atomic_pte+0x3a/0x50 mm/shmem.c:2440
mfill_atomic_pte mm/userfaultfd.c:449 [inline]
__mcopy_atomic mm/userfaultfd.c:582 [inline]
mcopy_atomic+0x84f/0x1ba0 mm/userfaultfd.c:632
userfaultfd_copy fs/userfaultfd.c:1743 [inline]
userfaultfd_ioctl+0x2289/0x4890 fs/userfaultfd.c:1941
vfs_ioctl fs/ioctl.c:47 [inline]
ksys_ioctl fs/ioctl.c:763 [inline]
__do_sys_ioctl fs/ioctl.c:772 [inline]
__se_sys_ioctl+0xf9/0x160 fs/ioctl.c:770
do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:295
entry_SYSCALL_64_after_hwframe+0x49/0xb3
RIP: 0033:0x444399
Code: 0d d8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 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 0f 83 db d7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffd0974a4a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 0000000000444399
RDX: 00000000200a0fe0 RSI: 00000000c028aa03 RDI: 0000000000000004
RBP: 00000000006cf018 R08: 00000000004002e0 R09: 00000000004002e0
R10: 00000000004002e0 R11: 0000000000000246 R12: 0000000000402000
R13: 0000000000402090 R14: 0000000000000000 R15: 0000000000000000

[syzbot]

syzbot has bisected this bug to:

commit 71725ed10c40696dc6bdccf8e225815dcef24dba
Author: Hugh Dickins <hu...@google.com>
Date: Tue Apr 7 03:07:57 2020 +0000

mm: huge tmpfs: try to split_huge_page() when punching hole

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=17c463e7e00000
start commit: ab6f762f printk: queue wake_up_klogd irq_work only if per-..
git tree: upstream
final crash: https://syzkaller.appspot.com/x/report.txt?x=142463e7e00000
console output: https://syzkaller.appspot.com/x/log.txt?x=102463e7e00000

kernel config: https://syzkaller.appspot.com/x/.config?x=3010ccb0f380f660
dashboard link: https://syzkaller.appspot.com/bug?extid=e27980339d305f2dbfd9

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12d3c5afe00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15e7f51be00000

Reported-by: syzbot+e27980...@syzkaller.appspotmail.com
Fixes: 71725ed10c40 ("mm: huge tmpfs: try to split_huge_page() when punching hole")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

[Yang Shi]

This looks possible. shmem_mfill_atomic_pte() acquires info->lock with
irq enabled.

The below patch should be able to fix it:

diff --git a/mm/shmem.c b/mm/shmem.c
index d722eb8..762da6a 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -2399,11 +2399,11 @@ static int shmem_mfill_atomic_pte(struct
mm_struct *dst_mm,

lru_cache_add_anon(page);

- spin_lock(&info->lock);
+ spin_lock_irq(&info->lock);
info->alloced++;
inode->i_blocks += BLOCKS_PER_PAGE;
shmem_recalc_inode(inode);
- spin_unlock(&info->lock);
+ spin_unlock_irq(&info->lock);

inc_mm_counter(dst_mm, mm_counter_file(page));
page_add_file_rmap(page, false);

[Hugh Dickins]

I agree, thank you: please send to akpm with your signoff and

Reported-by: syzbot+e27980...@syzkaller.appspotmail.com
Fixes: 4c27fe4c4c84 ("userfaultfd: shmem: add shmem_mcopy_atomic_pte for userfaultfd support")
Acked-by: Hugh Dickins <hu...@google.com>

I bet that 4.11 commit was being worked on before 4.8 reversed the
ordering of info->lock and tree_lock, changing spin_lock(&info->lock)s
to spin_lock_irq*(&info->lock)s - this one is the only hold-out; and
not using userfaultfd, I wouldn't have seen the lockdep report.

[Yang Shi]

Thanks, Hugh. I believe this commit could fix the splat. I'm trying to
push my test tree to github to let syzkaller test it. I will send the
formal patch once I get it tested. It is just slow to push to github,
less than 50KB/s...

[Hugh Dickins]

On Wed, 15 Apr 2020, Yang Shi wrote:
>
> Thanks, Hugh. I believe this commit could fix the splat. I'm trying to
> push my test tree to github to let syzkaller test it. I will send the
> formal patch once I get it tested. It is just slow to push to github,
> less than 50KB/s...

Your diligence is admirable. With straightforward ones like this,
I tend to just rely on syzbot to call me out later if I've bluffed.

Hugh

[Yang Shi]

#syz test: https://github.com/yang-shi/linux.git
8f9c86c99d278d375ae24b7ea426e1662c5e4009

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger crash:

Reported-and-tested-by: syzbot+e27980...@syzkaller.appspotmail.com

Tested on:

commit: 8f9c86c9 mm: shmem: disable interrupt when acquiring info-..
git tree: https://github.com/yang-shi/linux.git
kernel config: https://syzkaller.appspot.com/x/.config?x=11f10cc27c63cade

dashboard link: https://syzkaller.appspot.com/bug?extid=e27980339d305f2dbfd9
compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81)

Note: testing is done by a robot and is best-effort only.