RE: [PATCH v4 2/2] mm, hwpoison: When copy-on-write hits poison, take page offline

[Luck, Tony]

Jane,

You should do some analysis and testing to make sure that applying just this patch to 5.15.y works. There has been a bunch of recovery changes and I'm not sure if this depends on other changes.

-Tony

-----Original Message-----
From: Jane Chu <jane.chu@xxxxxxxxxx> 
Sent: Thursday, May 18, 2023 2:50 PM
To: Luck, Tony <tony.luck@xxxxxxxxx>; Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>; Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>; Naoya Horiguchi <naoya.horiguchi@xxxxxxx>; Miaohe Lin <linmiaohe@xxxxxxxxxx>; Matthew Wilcox <willy@xxxxxxxxxxxxx>; Shuai Xue <xueshuai@xxxxxxxxxxxxxxxxx>; Williams, Dan J <dan.j.williams@xxxxxxxxx>; linux-mm@xxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
Subject: Re: [PATCH v4 2/2] mm, hwpoison: When copy-on-write hits poison, take page offline

Hi, Tony, Greg,

Does it make sense to include this patch series in the
5.15.y LTS kernel?  I just checked: it's not in 5.15.112.

Thanks!
-jane


On 10/31/2022 1:10 PM, Tony Luck wrote:
> Cannot call memory_failure() directly from the fault handler because
> mmap_lock (and others) are held.
> 
> It is important, but not urgent, to mark the source page as h/w poisoned
> and unmap it from other tasks.
> 
> Use memory_failure_queue() to request a call to memory_failure() for the
> page with the error.
> 
> Also provide a stub version for CONFIG_MEMORY_FAILURE=n
> 
> Reviewed-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
> Tested-by: Shuai Xue <xueshuai@xxxxxxxxxxxxxxxxx>
> Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
> Message-Id: <20221021200120.175753-3-tony.luck@xxxxxxxxx>
> Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
> ---
>   include/linux/mm.h | 5 ++++-
>   mm/memory.c        | 4 +++-
>   2 files changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 8bbcccbc5565..03ced659eb58 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -3268,7 +3268,6 @@ enum mf_flags {
>   int mf_dax_kill_procs(struct address_space *mapping, pgoff_t index,
>   		      unsigned long count, int mf_flags);
>   extern int memory_failure(unsigned long pfn, int flags);
> -extern void memory_failure_queue(unsigned long pfn, int flags);
>   extern void memory_failure_queue_kick(int cpu);
>   extern int unpoison_memory(unsigned long pfn);
>   extern int sysctl_memory_failure_early_kill;
> @@ -3277,8 +3276,12 @@ extern void shake_page(struct page *p);
>   extern atomic_long_t num_poisoned_pages __read_mostly;
>   extern int soft_offline_page(unsigned long pfn, int flags);
>   #ifdef CONFIG_MEMORY_FAILURE
> +extern void memory_failure_queue(unsigned long pfn, int flags);
>   extern int __get_huge_page_for_hwpoison(unsigned long pfn, int flags);
>   #else
> +static inline void memory_failure_queue(unsigned long pfn, int flags)
> +{
> +}
>   static inline int __get_huge_page_for_hwpoison(unsigned long pfn, int flags)
>   {
>   	return 0;
> diff --git a/mm/memory.c b/mm/memory.c
> index b6056eef2f72..eae242351726 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -2866,8 +2866,10 @@ static inline int __wp_page_copy_user(struct page *dst, struct page *src,
>   	unsigned long addr = vmf->address;
>   
>   	if (likely(src)) {
> -		if (copy_mc_user_highpage(dst, src, addr, vma))
> +		if (copy_mc_user_highpage(dst, src, addr, vma)) {
> +			memory_failure_queue(page_to_pfn(src), 0);
>   			return -EHWPOISON;
> +		}
>   		return 0;
>   	}
>