On Mon, Jul 17, 2023 at 07:30:08PM +0000, SeongJae Park wrote:
From: Ryan Roberts ryan.roberts@arm.com
commit c11d34fa139e4b0fb4249a30f37b178353533fa1 upstream.
It is racy to non-atomically read a pte, then clear the young bit, then write it back as this could discard dirty information. Further, it is bad practice to directly set a pte entry within a table. Instead clearing young must go through the arch-provided helper, ptep_test_and_clear_young() to ensure it is modified atomically and to give the arch code visibility and allow it to check (and potentially modify) the operation.
Link: https://lkml.kernel.org/r/20230602092949.545577-3-ryan.roberts@arm.com Fixes: 3f49584b262c ("mm/damon: implement primitives for the virtual memory address spaces"). Signed-off-by: Ryan Roberts ryan.roberts@arm.com Reviewed-by: Zi Yan ziy@nvidia.com Reviewed-by: SeongJae Park sj@kernel.org Reviewed-by: Mike Rapoport (IBM) rppt@kernel.org Cc: Christoph Hellwig hch@lst.de Cc: Kirill A. Shutemov kirill.shutemov@linux.intel.com Cc: Lorenzo Stoakes lstoakes@gmail.com Cc: Matthew Wilcox (Oracle) willy@infradead.org Cc: Uladzislau Rezki (Sony) urezki@gmail.com Cc: Yu Zhao yuzhao@google.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: SeongJae Park sj@kernel.org
This is a manual backport of the commit, which cannot cleanly cherry-picked on 5.15.y[1], on 5.15.y, specifically 5.15.120.
[1] https://lore.kernel.org/stable/2023071613-reminder-relapse-b922@gregkh/
Now queued up, thanks.
greg k-h