Re: [PATCH v5 1/3] mm/memory-failure: Use a mutex to avoid memory_failure() races

[Oscar Salvador]

On Fri, May 21, 2021 at 12:01:54PM +0900, Naoya Horiguchi wrote:
> From: Tony Luck <tony.luck@xxxxxxxxx>
> 
> There can be races when multiple CPUs consume poison from the same
> page. The first into memory_failure() atomically sets the HWPoison
> page flag and begins hunting for tasks that map this page. Eventually
> it invalidates those mappings and may send a SIGBUS to the affected
> tasks.
> 
> But while all that work is going on, other CPUs see a "success"
> return code from memory_failure() and so they believe the error
> has been handled and continue executing.
> 
> Fix by wrapping most of the internal parts of memory_failure() in
> a mutex.
> 
> Signed-off-by: Tony Luck <tony.luck@xxxxxxxxx>
> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
> Reviewed-by: Borislav Petkov <bp@xxxxxxx>

Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>


-- 
Oscar Salvador
SUSE L3