Re: [PATCH stable/linux-6.6.y] mm/memory-failure: fix missing ->mf_stats count when hugetlb folio already poisoned

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, Jul 14, 2026 at 09:45:03AM +0800, Qi Xi wrote:
> Add stable@ to Cc.
> 
> On 06/07/2026 16:41, Qi Xi wrote:
> > When a new subpage is poisoned on a hugetlb folio that has already been
> > marked hwpoison (MF_HUGETLB_FOLIO_PRE_POISONED), hugetlb_update_hwpoison()
> > increments num_poisoned_pages directly, but the per-node ->mf_stats is
> > not updated because this path bypasses action_result(). This leaves the
> > two accounting counters inconsistent within the hardware memory-failure
> > path: a new poison event is counted in num_poisoned_pages but not reflected
> > in the per-node mf_stats.
> > 
> > In mainline, commit a148a2040191 ("mm/memory-failure: fix missing
> > ->mf_stats count in hugetlb poison") fixed this by removing the direct
> > num_poisoned_pages_inc() from the helper and adding action_result() calls
> > in try_memory_failure_hugetlb() for the already-poisoned cases. The
> > backport to linux-6.6.y as commit 252bb328b36f ("mm/memory-failure: fix
> > missing ->mf_stats count in hugetlb poison") applied the refactoring
> > (naming, constants, switch-case) but omitted the core counting fix,
> > leaving the inconsistency in place.
> > 
> > Fix this by adding a matching update_per_node_mf_stats() call alongside
> > the existing num_poisoned_pages_inc() in the same block, so both counters
> > stay consistent without restructuring the error path.
> > 
> > Fixes: 252bb328b36f ("mm/memory-failure: fix missing ->mf_stats count in hugetlb poison")
> > Signed-off-by: Qi Xi <xiqi2@huawei.com>

We need acks/reviews by the relevant maintainers before we can accept
something like this.

thanks,

greg k-h