Re: [PATCH resend] mm/memory-failure: fix hugetlb_lock AA deadlock in get_huge_page_for_hwpoison

[Miaohe Lin <linmiaohe@huawei.com>]

On 2026/5/22 9:03, Wupeng Ma wrote:
> Two concurrent madvise(MADV_HWPOISON) calls on the same hugetlb page
> can trigger a recursive spinlock self-deadlock (AA deadlock) on
> hugetlb_lock when racing with a concurrent unmap:
> 
>   thread#0                              thread#1
>   --------                              --------
>   madvise(folio, MADV_HWPOISON)
>     -> poisons the folio successfully
>   madvise(folio, MADV_HWPOISON)         unmap(folio)
>     try_memory_failure_hugetlb
>       get_huge_page_for_hwpoison
>         spin_lock_irq(&hugetlb_lock)    <- held
>         __get_huge_page_for_hwpoison
>           hugetlb_update_hwpoison()
>             -> MF_HUGETLB_FOLIO_PRE_POISONED
>           goto out:
>             folio_put()
>               refcount: 1 -> 0
>               free_huge_folio()
>                 spin_lock_irqsave(&hugetlb_lock)
>                   -> AA DEADLOCK!
> 
> The out: path in __get_huge_page_for_hwpoison() calls folio_put() to
> drop the GUP reference while the hugetlb_lock is still held by the
> hugetlb.c wrapper get_huge_page_for_hwpoison().  If concurrent unmap
> has released the page table mapping reference, folio_put() drops the
> folio refcount to zero, triggering free_huge_folio() which attempts
> to re-acquire the non-recursive hugetlb_lock.
> 
> Fix this by moving hugetlb_lock acquisition from the hugetlb.c wrapper
> into get_huge_page_for_hwpoison().  Place spin_unlock_irq() before the
> folio_put() at the out: label so the folio is always released outside
> the lock.
> 
> Fixes: 405ce051236c ("mm/hwpoison: fix race between hugetlb free/demotion and memory_failure_hugetlb()")
> Signed-off-by: Wupeng Ma <mawupeng1@huawei.com>

Thanks for your patch.

> ---
> Changelog since v3[1]:
>  - update commit message to fit current issue  
> 
> [1]: https://lore.kernel.org/linux-mm/20260520020128.3506168-1-mawupeng1@huawei.com/ 
> ---
>  include/linux/hugetlb.h |  8 --------
>  include/linux/mm.h      |  8 --------
>  mm/hugetlb.c            | 11 -----------
>  mm/memory-failure.c     |  8 ++++----
>  4 files changed, 4 insertions(+), 31 deletions(-)
> 
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index 93418625d3c5..059749ed519f 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -153,8 +153,6 @@ long hugetlb_unreserve_pages(struct inode *inode, long start, long end,
>  						long freed);
>  bool folio_isolate_hugetlb(struct folio *folio, struct list_head *list);
>  int get_hwpoison_hugetlb_folio(struct folio *folio, bool *hugetlb, bool unpoison);
> -int get_huge_page_for_hwpoison(unsigned long pfn, int flags,
> -				bool *migratable_cleared);
>  void folio_putback_hugetlb(struct folio *folio);
>  void move_hugetlb_state(struct folio *old_folio, struct folio *new_folio, int reason);
>  void hugetlb_fix_reserve_counts(struct inode *inode);
> @@ -422,12 +420,6 @@ static inline int get_hwpoison_hugetlb_folio(struct folio *folio, bool *hugetlb,
>  	return 0;
>  }
> 
> -static inline int get_huge_page_for_hwpoison(unsigned long pfn, int flags,
> -					bool *migratable_cleared)
> -{
> -	return 0;
> -}
> -
>  static inline void folio_putback_hugetlb(struct folio *folio)
>  {
>  }
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 0b776907152e..4c4d1a61a6a7 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -4975,8 +4975,6 @@ extern int soft_offline_page(unsigned long pfn, int flags);
>   */
>  extern const struct attribute_group memory_failure_attr_group;
>  extern void memory_failure_queue(unsigned long pfn, int flags);
> -extern int __get_huge_page_for_hwpoison(unsigned long pfn, int flags,
> -					bool *migratable_cleared);
>  void num_poisoned_pages_inc(unsigned long pfn);
>  void num_poisoned_pages_sub(unsigned long pfn, long i);
>  #else
> @@ -4984,12 +4982,6 @@ static inline void memory_failure_queue(unsigned long pfn, int flags)
>  {
>  }
> 
> -static inline int __get_huge_page_for_hwpoison(unsigned long pfn, int flags,
> -					bool *migratable_cleared)
> -{
> -	return 0;
> -}
> -
>  static inline void num_poisoned_pages_inc(unsigned long pfn)
>  {
>  }
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index f24bf49be047..67243923fa24 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -7154,17 +7154,6 @@ int get_hwpoison_hugetlb_folio(struct folio *folio, bool *hugetlb, bool unpoison
>  	return ret;
>  }
> 
> -int get_huge_page_for_hwpoison(unsigned long pfn, int flags,
> -				bool *migratable_cleared)
> -{
> -	int ret;
> -
> -	spin_lock_irq(&hugetlb_lock);
> -	ret = __get_huge_page_for_hwpoison(pfn, flags, migratable_cleared);
> -	spin_unlock_irq(&hugetlb_lock);
> -	return ret;
> -}
> -
>  /**
>   * folio_putback_hugetlb - unisolate a hugetlb folio
>   * @folio: the isolated hugetlb folio
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index ee42d4361309..28522180cf7f 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1966,10 +1966,7 @@ void folio_clear_hugetlb_hwpoison(struct folio *folio)
>  	folio_free_raw_hwp(folio, true);
>  }
> 
> -/*
> - * Called from hugetlb code with hugetlb_lock held.
> - */
> -int __get_huge_page_for_hwpoison(unsigned long pfn, int flags,
> +static int get_huge_page_for_hwpoison(unsigned long pfn, int flags,
>  				 bool *migratable_cleared)
>  {
>  	struct page *page = pfn_to_page(pfn);
> @@ -1977,6 +1974,7 @@ int __get_huge_page_for_hwpoison(unsigned long pfn, int flags,
>  	bool count_increased = false;
>  	int ret, rc;
> 
> +	spin_lock_irq(&hugetlb_lock);
>  	if (!folio_test_hugetlb(folio)) {
>  		ret = MF_HUGETLB_NON_HUGEPAGE;
>  		goto out;
> @@ -2013,8 +2011,10 @@ int __get_huge_page_for_hwpoison(unsigned long pfn, int flags,
>  		*migratable_cleared = true;
>  	}
> 
> +	spin_unlock_irq(&hugetlb_lock);
>  	return ret;
>  out:

It might be better to rename out: as out_unlock. But that's trivial.

Acked-by: Miaohe Lin <linmiaohe@huawei.com>

Thanks.
.