Re: [RFC PATCH] mm/memory-failure: release private data before split THP

["HORIGUCHI NAOYA(堀口 直也)" <naoya.horiguchi@nec.com>]

On Wed, Aug 03, 2022 at 10:52:43AM +0800, Yin Fengwei wrote:
> If there is private data attached to THP, the refcount of
> THP will be increased and block the THP split. Which could
> further cause the meomry failure not recovered.
> 
> Release private data attached to THP before split it to
> increase the chance of splitting THP successfully.
> 
> The issue was hit during HW error injection testing with
> 5.18 kernel + xfs as rootfs, test got killed and system
> reboot was required to re-run the test.
> 
> The issue was tracked down to THP split failure caused the
> memory failure not being handled. The page dump showed:
> 
> [ 1785.433075] page:0000000025f9530b refcount:18 mapcount:0 mapping:000000008162eea7 index:0xa10 pfn:0x2f0200
> [ 1785.443954] head:0000000025f9530b order:4 compound_mapcount:0 compound_pincount:0
> [ 1785.452408] memcg:ff4247f2d28e9000
> [ 1785.456304] aops:xfs_address_space_operations ino:8555182 dentry name:"baseos-filenames.solvx"
> [ 1785.466612] flags: 0x1000000000012036(referenced|uptodate|lru|active|private|head|node=0|zone=2)
> [ 1785.476514] raw: 1000000000012036 ffb9460f8bc07c08 ffb9460f8bc08408 ff4247f22e6299f8
> [ 1785.485268] raw: 0000000000000a10 ff4247f194ade900 00000012ffffffff ff4247f2d28e9000
> 
> It was like the error was injected to a large folio for xfs with
> private data attached.
> 
> With private data released before split THP, the test case
> could be run successfully many times without reboot system.
> 
> Signed-off-by: Yin Fengwei <fengwei.yin@intel.com>
> Reviewed-by: Aaron Lu <aaron.lu@intel.com>

Thank you for the patch,
It looks reasonable to me so far.

Reviewed-by: Naoya Horiguchi <naoya.horiguchi@nec.com>