Re: WARNING in memory_failure() at include/linux/huge_mm.h:635 triggered

[jane.chu@oracle.com]

On 2/4/2026 1:41 PM, Zi Yan wrote:
> On 4 Feb 2026, at 16:37, David Hildenbrand (arm) wrote:
> 
>> On 2/4/26 22:08, Zi Yan wrote:
>>> On 4 Feb 2026, at 14:18, David Hildenbrand (arm) wrote:
>>>
>>>> On 2/4/26 18:41, Zi Yan wrote:
>>>>>
>>>>>
>>>>> More details:
>>>>> later at sg_vma_fault(), the driver just handles a page fault by supplying
>>>>> a subpage from a pre-allocated compound page[3]. We then get a large folio
>>>>> without !CONFIG_TRANSPARENT_HUGEPAGE.
>>>>
>>>> We can identify such non-folio (but compound) things by looking at PG_large_rmappable IIRC.
>>>
>>> OK, back to the issue. The patch below should fix the issue?
>>>
>>> Hi 是参差,
>>>
>>> Can you test it?
>>>
> 
> <snip>
>> I think you have to test for folio_test_large() before testing folio_test_large_rmappable().
> 
> Oh, forgot that. Thanks.
> 
> 
>  From 8dda4bba9964890462eca3ef3cce57bb4fab8313 Mon Sep 17 00:00:00 2001
> From: Zi Yan <ziy@nvidia.com>
> Date: Wed, 4 Feb 2026 16:04:19 -0500
> Subject: [PATCH] mm/memory_failure: reject unsupported non-folio compound page
> 
> Signed-off-by: Zi Yan <ziy@nvidia.com>
> ---
>   mm/memory-failure.c | 8 ++++++--
>   1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 825c706ac576..137c67fda57e 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -2440,9 +2440,13 @@ int memory_failure(unsigned long pfn, int flags)
> 
>   	folio = page_folio(p);
> 
> -	/* filter pages that are protected from hwpoison test by users */
> +	/*
> +	 * filter pages that are protected from hwpoison test by users
> +	 * or unsupported non folio compound pages
> +	 */
>   	folio_lock(folio);
> -	if (hwpoison_filter(p)) {
> +	if (hwpoison_filter(p) ||
> +	    (folio_test_large(folio) && !folio_test_large_rmappable(folio))) {

Just curious, would this filter out pte-mapped THP/mTHP folios?

>   		ClearPageHWPoison(p);
>   		folio_unlock(folio);
>   		folio_put(folio);

thanks,
-jane