linux-kernel - Re: [PATCH v2] mm/memory-failure: Fix redundant updates for already poisoned pages

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Message-ID: <CACw3F50kFq4V9+-JUdi+PEYbNUkOJZHPOy4VCowhKXW-sB=Ugw@mail.gmail.com>
Date: Thu, 28 Aug 2025 12:58:50 -0700
From: Jiaqi Yan <jiaqiyan@...gle.com>
To: Kyle Meyer <kyle.meyer@....com>
Cc: akpm@...ux-foundation.org, linmiaohe@...wei.com, jane.chu@...cle.com, 
	bp@...en8.de, david@...hat.com, Liam.Howlett@...cle.com, 
	linux-edac@...r.kernel.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org, 
	lorenzo.stoakes@...cle.com, mhocko@...e.com, nao.horiguchi@...il.com, 
	osalvador@...e.de, rppt@...nel.org, russ.anderson@....com, surenb@...gle.com, 
	tony.luck@...el.com, vbabka@...e.cz
Subject: Re: [PATCH v2] mm/memory-failure: Fix redundant updates for already
 poisoned pages

On Thu, Aug 28, 2025 at 11:38 AM Kyle Meyer <kyle.meyer@....com> wrote:
>
> Duplicate memory errors can be reported by multiple sources.
>
> Passing an already poisoned page to action_result() causes issues:
>
> * The amount of hardware corrupted memory is incorrectly updated.
> * Per NUMA node MF stats are incorrectly updated.
> * Redundant "already poisoned" messages are printed.
>
> Avoid those issues by:
>
> * Skipping hardware corrupted memory updates for already poisoned pages.
> * Skipping per NUMA node MF stats updates for already poisoned pages.
> * Dropping redundant "already poisoned" messages.
>
> Make MF_MSG_ALREADY_POISONED consistent with other action_page_types and
> make calls to action_result() consistent for already poisoned
> normal pages and huge pages.
>
> Fixes: b8b9488d50b7 ("mm/memory-failure: improve memory failure action_result messages")
> Signed-off-by: Kyle Meyer <kyle.meyer@....com>
> ---
>
> v1 -> v2:
>  * Continue passing poisoned pages to action_result() with MF_FAILED but don't
> update anything.
>  * https://lore.kernel.org/all/20250821164445.14467-1-kyle.meyer@hpe.com
>
> ---
>  mm/memory-failure.c | 13 ++++++-------
>  1 file changed, 6 insertions(+), 7 deletions(-)
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index fc30ca4804bf..10b3c281c2ae 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -956,7 +956,7 @@ static const char * const action_page_types[] = {
>         [MF_MSG_BUDDY]                  = "free buddy page",
>         [MF_MSG_DAX]                    = "dax page",
>         [MF_MSG_UNSPLIT_THP]            = "unsplit thp",
> -       [MF_MSG_ALREADY_POISONED]       = "already poisoned",
> +       [MF_MSG_ALREADY_POISONED]       = "already poisoned page",
>         [MF_MSG_UNKNOWN]                = "unknown page",
>  };
>
> @@ -1349,9 +1349,10 @@ static int action_result(unsigned long pfn, enum mf_action_page_type type,
>  {
>         trace_memory_failure_event(pfn, type, result);
>
> -       num_poisoned_pages_inc(pfn);
> -
> -       update_per_node_mf_stats(pfn, result);
> +       if (type != MF_MSG_ALREADY_POISONED) {
> +               num_poisoned_pages_inc(pfn);
> +               update_per_node_mf_stats(pfn, result);
> +       }

Thanks Kyle, the code looks good to me. While you wait for Miaohe's
review/ack...

Reviewed-by: Jiaqi Yan <jiaqiyan@...gle.com>

>
>         pr_err("%#lx: recovery action for %s: %s\n",
>                 pfn, action_page_types[type], action_name[result]);
> @@ -2094,12 +2095,11 @@ static int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb
>                 *hugetlb = 0;
>                 return 0;
>         } else if (res == -EHWPOISON) {
> -               pr_err("%#lx: already hardware poisoned\n", pfn);
>                 if (flags & MF_ACTION_REQUIRED) {
>                         folio = page_folio(p);
>                         res = kill_accessing_process(current, folio_pfn(folio), flags);
> -                       action_result(pfn, MF_MSG_ALREADY_POISONED, MF_FAILED);
>                 }
> +               action_result(pfn, MF_MSG_ALREADY_POISONED, MF_FAILED);
>                 return res;
>         } else if (res == -EBUSY) {
>                 if (!(flags & MF_NO_RETRY)) {
> @@ -2285,7 +2285,6 @@ int memory_failure(unsigned long pfn, int flags)
>                 goto unlock_mutex;
>
>         if (TestSetPageHWPoison(p)) {
> -               pr_err("%#lx: already hardware poisoned\n", pfn);
>                 res = -EHWPOISON;
>                 if (flags & MF_ACTION_REQUIRED)
>                         res = kill_accessing_process(current, pfn, flags);
> --
> 2.50.1
>