Re: [syzbot] BUG: soft lockup in get_page_from_freelist

[Dmitry Vyukov]

On Thu, Mar 25, 2021 at 7:48 PM syzbot
<syzbot+b6c93d85a3f77fca7f13@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    e1381380 Merge git://git.kernel.org/pub/scm/linux/kernel/g..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=11238fb2d00000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=460abe93fbc821a4
> dashboard link: https://syzkaller.appspot.com/bug?extid=b6c93d85a3f77fca7f13
> userspace arch: arm
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+b6c93d85a3f77fca7f13@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [syz-executor.1:22367]

/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\

This is also due to arm64 removal of CMDLINE support.
syzbot sets watchdog_thresh=165, but this fired after 22s.

#syz dup: BUG: soft lockup in do_wp_page (4)


> Modules linked in:
> irq event stamp: 4562
> hardirqs last  enabled at (4561): [<ffff8000143e4dd8>] exit_to_kernel_mode+0x38/0x230 arch/arm64/kernel/entry-common.c:59
> hardirqs last disabled at (4562): [<ffff8000143e54a0>] enter_el1_irq_or_nmi+0x10/0x20 arch/arm64/kernel/entry-common.c:101
> softirqs last  enabled at (4442): [<ffff8000100109e0>] _stext+0x9e0/0x1084
> softirqs last disabled at (4203): [<ffff80001015a04c>] do_softirq_own_stack include/asm-generic/softirq_stack.h:10 [inline]
> softirqs last disabled at (4203): [<ffff80001015a04c>] invoke_softirq kernel/softirq.c:228 [inline]
> softirqs last disabled at (4203): [<ffff80001015a04c>] __irq_exit_rcu+0x46c/0x510 kernel/softirq.c:422
> CPU: 0 PID: 22367 Comm: syz-executor.1 Not tainted 5.12.0-rc4-syzkaller-00223-ge138138003eb #0
> Hardware name: linux,dummy-virt (DT)
> pstate: 00000005 (nzcv daif -PAN -UAO -TCO BTYPE=--)
> pc : clear_page+0x14/0x28 arch/arm64/lib/clear_page.S:23
> lr : clear_highpage include/linux/highmem.h:203 [inline]
> lr : kernel_init_free_pages+0x74/0x180 mm/page_alloc.c:1212
> sp : ffff0000105e7630
> x29: ffff0000105e7630 x28: fffffc0000180f00
> x27: ffff00007fc13ec0 x26: ffff00000a7be378
> x25: ffff6000014f7c6f x24: 00000000000014b8
> x23: ffff00000a7bcec0 x22: fffffc0000180f40
> x21: ffff8000154f3398 x20: dfff800000000000
> x19: fffffc0000180f00 x18: 0000000000000000
> x17: 0000000000000000 x16: 0000000000000000
> x15: 0000000000000000 x14: 1fffe000020bce90
> x13: 0000000000000001 x12: ffff7f80000301e7
> x11: 1fffff80000301e6 x10: ffff7f80000301e6
> x9 : 0000000000000000 x8 : ffff600000c07a00
> x7 : 0000000000000000 x6 : 000000000000003f
> x5 : 0000000000000040 x4 : 1ffff00002fa7950
> x3 : 1fffe000014f79d9 x2 : 0000000000000004
> x1 : 0000000000000040 x0 : ffff00000603cf40
> Call trace:
>  clear_page+0x14/0x28 arch/arm64/lib/clear_page.S:21
>  post_alloc_hook+0x130/0x1fc mm/page_alloc.c:2305
>  prep_new_page mm/page_alloc.c:2311 [inline]
>  get_page_from_freelist+0x2024/0x2a40 mm/page_alloc.c:3951
>  __alloc_pages_nodemask+0x2a0/0x24dc mm/page_alloc.c:5001
>  alloc_pages_vma+0xb4/0x510 mm/mempolicy.c:2240
>  alloc_zeroed_user_highpage_movable include/linux/highmem.h:197 [inline]
>  do_anonymous_page mm/memory.c:3548 [inline]
>  handle_pte_fault mm/memory.c:4316 [inline]
>  __handle_mm_fault+0xc88/0x21d4 mm/memory.c:4453
>  handle_mm_fault+0x1cc/0x4dc mm/memory.c:4551
>  __do_page_fault arch/arm64/mm/fault.c:507 [inline]
>  do_page_fault+0x228/0x880 arch/arm64/mm/fault.c:591
>  do_translation_fault+0x1a4/0x210 arch/arm64/mm/fault.c:672
>  do_mem_abort+0x64/0x1c0 arch/arm64/mm/fault.c:805
>  el0_da+0x3c/0x50 arch/arm64/kernel/entry-common.c:308
>  el0_sync_compat_handler+0x114/0x140 arch/arm64/kernel/entry-common.c:506
>  el0_sync_compat+0x174/0x180 arch/arm64/kernel/entry.S:708
>
>
> ---
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