On Tue, 29 Oct 2019 23:25:13 +0200 Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx> wrote:
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> I got some khugepaged spew on a 32bit x86:
>
> [ 217.490026] BUG: sleeping function called from invalid context at include/linux/mmu_notifier.h:346
> [ 217.492826] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 25, name: khugepaged
> [ 217.495589] INFO: lockdep is turned off.
> [ 217.498371] CPU: 1 PID: 25 Comm: khugepaged Not tainted 5.4.0-rc5-elk+ #206
> [ 217.501233] Hardware name: System manufacturer P5Q-EM/P5Q-EM, BIOS 2203 07/08/2009
> [ 217.501697] Call Trace:
> [ 217.501697] dump_stack+0x66/0x8e
> [ 217.501697] ___might_sleep.cold.96+0x95/0xa6
> [ 217.501697] __might_sleep+0x2e/0x80
> [ 217.501697] collapse_huge_page.isra.51+0x5ac/0x1360
> [ 217.501697] ? __alloc_pages_nodemask+0xec/0xf80
> [ 217.501697] ? __alloc_pages_nodemask+0x191/0xf80
> [ 217.501697] ? trace_hardirqs_on+0x4a/0xf0
> [ 217.501697] khugepaged+0x9a9/0x20f0
> [ 217.501697] ? _raw_spin_unlock+0x21/0x30
> [ 217.501697] ? trace_hardirqs_on+0x4a/0xf0
> [ 217.501697] ? wait_woken+0xa0/0xa0
> [ 217.501697] kthread+0xf5/0x110
> [ 217.501697] ? collapse_pte_mapped_thp+0x3b0/0x3b0
> [ 217.501697] ? kthread_create_worker_on_cpu+0x20/0x20
> [ 217.501697] ret_from_fork+0x2e/0x38
>
> Looks like it's due to CONFIG_HIGHPTE=y pte_offset_map()->kmap_atomic()
> vs. mmu_notifier_invalidate_range_start(). Let's do the naive approach
> and just reorder the two operations.
Thanks.
I'll add
Fixes: 810e24e009cf71 ("mm/mmu_notifiers: annotate with might_sleep()")
Cc: <stable@xxxxxxxxxxxxxxx>
although 810e24e009cf71 merely exposed the bug.
