kernel panic: corrupted stack end in wb_workfn

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    195303136f19 Merge tag 'kconfig-v4.21-2' of git://git.kern..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=176c0ebf400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5e7dc790609552d7
dashboard link: https://syzkaller.appspot.com/bug?extid=ec1b7575afef85a0e5ca
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16a9a84b400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17199bb3400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+ec1b7575afef85a0e5ca@xxxxxxxxxxxxxxxxxxxxxxxxx

Kernel panic - not syncing: corrupted stack end detected inside scheduler
CPU: 0 PID: 7 Comm: kworker/u4:0 Not tainted 4.20.0+ #396
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: writeback wb_workfn (flush-8:0)
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1d3/0x2c6 lib/dump_stack.c:113
 panic+0x2ad/0x55f kernel/panic.c:189
 schedule_debug kernel/sched/core.c:3285 [inline]
 __schedule+0x1ec6/0x1ed0 kernel/sched/core.c:3394
 preempt_schedule_common+0x1f/0xe0 kernel/sched/core.c:3596
 preempt_schedule+0x4d/0x60 kernel/sched/core.c:3622
 ___preempt_schedule+0x16/0x18
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:161 [inline]
 _raw_spin_unlock_irqrestore+0xbb/0xd0 kernel/locking/spinlock.c:184
 spin_unlock_irqrestore include/linux/spinlock.h:384 [inline]
 __remove_mapping+0x932/0x1af0 mm/vmscan.c:967
 shrink_page_list+0x6610/0xc2e0 mm/vmscan.c:1461
 shrink_inactive_list+0x77b/0x1c60 mm/vmscan.c:1961
 shrink_list mm/vmscan.c:2273 [inline]
 shrink_node_memcg+0x7a8/0x19a0 mm/vmscan.c:2538
 shrink_node+0x3e1/0x17f0 mm/vmscan.c:2753
 shrink_zones mm/vmscan.c:2987 [inline]
 do_try_to_free_pages+0x3df/0x12a0 mm/vmscan.c:3049
 try_to_free_pages+0x4d0/0xb90 mm/vmscan.c:3265
 __perform_reclaim mm/page_alloc.c:3920 [inline]
 __alloc_pages_direct_reclaim mm/page_alloc.c:3942 [inline]
 __alloc_pages_slowpath+0xa5a/0x2db0 mm/page_alloc.c:4335
 __alloc_pages_nodemask+0xa89/0xde0 mm/page_alloc.c:4549
 alloc_pages_current+0x10c/0x210 mm/mempolicy.c:2106
 alloc_pages include/linux/gfp.h:509 [inline]
 __page_cache_alloc+0x38c/0x5b0 mm/filemap.c:924
 pagecache_get_page+0x396/0xf00 mm/filemap.c:1615
 find_or_create_page include/linux/pagemap.h:322 [inline]
 ext4_mb_load_buddy_gfp+0xddf/0x1e70 fs/ext4/mballoc.c:1158
 ext4_mb_load_buddy fs/ext4/mballoc.c:1241 [inline]
 ext4_mb_regular_allocator+0x634/0x1590 fs/ext4/mballoc.c:2190
 ext4_mb_new_blocks+0x1de3/0x4840 fs/ext4/mballoc.c:4538
 ext4_ext_map_blocks+0x2eef/0x6180 fs/ext4/extents.c:4404
 ext4_map_blocks+0x8f7/0x1b60 fs/ext4/inode.c:636
 mpage_map_one_extent fs/ext4/inode.c:2480 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2533 [inline]
 ext4_writepages+0x2564/0x4170 fs/ext4/inode.c:2884
 do_writepages+0x9a/0x1a0 mm/page-writeback.c:2335
 __writeback_single_inode+0x20a/0x1660 fs/fs-writeback.c:1316
 writeback_sb_inodes+0x71f/0x1210 fs/fs-writeback.c:1580
 __writeback_inodes_wb+0x1b9/0x340 fs/fs-writeback.c:1649
 wb_writeback+0xa73/0xfc0 fs/fs-writeback.c:1758
oom_reaper: reaped process 7963 (syz-executor189), now anon-rss:0kB,  
file-rss:0kB, shmem-rss:0kB
rsyslogd invoked oom-killer: gfp_mask=0x6200ca(GFP_HIGHUSER_MOVABLE),  
order=0, oom_score_adj=0
 wb_check_start_all fs/fs-writeback.c:1882 [inline]
 wb_do_writeback fs/fs-writeback.c:1908 [inline]
 wb_workfn+0xee9/0x1790 fs/fs-writeback.c:1942
 process_one_work+0xc90/0x1c40 kernel/workqueue.c:2153
 worker_thread+0x17f/0x1390 kernel/workqueue.c:2296
 kthread+0x35a/0x440 kernel/kthread.c:246
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:352
CPU: 1 PID: 7840 Comm: rsyslogd Not tainted 4.20.0+ #396
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+0x1d3/0x2c6 lib/dump_stack.c:113
 dump_header+0x253/0x1239 mm/oom_kill.c:451
 oom_kill_process.cold.27+0x10/0x903 mm/oom_kill.c:966
 out_of_memory+0x8ba/0x1480 mm/oom_kill.c:1133
 __alloc_pages_may_oom mm/page_alloc.c:3666 [inline]
 __alloc_pages_slowpath+0x230c/0x2db0 mm/page_alloc.c:4379
 __alloc_pages_nodemask+0xa89/0xde0 mm/page_alloc.c:4549
 alloc_pages_current+0x10c/0x210 mm/mempolicy.c:2106
 alloc_pages include/linux/gfp.h:509 [inline]
 __page_cache_alloc+0x38c/0x5b0 mm/filemap.c:924
 page_cache_read mm/filemap.c:2373 [inline]
 filemap_fault+0x1595/0x25f0 mm/filemap.c:2557
 ext4_filemap_fault+0x82/0xad fs/ext4/inode.c:6317
 __do_fault+0x100/0x6b0 mm/memory.c:2997
 do_read_fault mm/memory.c:3409 [inline]
 do_fault mm/memory.c:3535 [inline]
 handle_pte_fault mm/memory.c:3766 [inline]
 __handle_mm_fault+0x392f/0x5630 mm/memory.c:3890
 handle_mm_fault+0x54f/0xc70 mm/memory.c:3927
 do_user_addr_fault arch/x86/mm/fault.c:1475 [inline]
 __do_page_fault+0x5f6/0xd70 arch/x86/mm/fault.c:1541
 do_page_fault+0xf2/0x7e0 arch/x86/mm/fault.c:1572
 page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1143
RIP: 0033:0x7f00f990e1fd
Code: Bad RIP value.
RSP: 002b:00007f00f6eade30 EFLAGS: 00010293
RAX: 0000000000000fd2 RBX: 000000000111f170 RCX: 00007f00f990e1fd
RDX: 0000000000000fff RSI: 00007f00f86e25a0 RDI: 0000000000000004
RBP: 0000000000000000 R08: 000000000110a260 R09: 0000000000000000
R10: 74616c7567657227 R11: 0000000000000293 R12: 000000000065e420
R13: 00007f00f6eae9c0 R14: 00007f00f9f53040 R15: 0000000000000003
Kernel Offset: disabled
Rebooting in 86400 seconds..


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