mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
synced 2025-01-16 05:26:07 +00:00
536ab838a5
It was recently observed at [1] that during the folio unmapping stage of migration, when the PTEs are cleared, a racing thread faulting on that folio may increase the refcount of the folio, sleep on the folio lock (the migration path has the lock), and migration ultimately fails when asserting the actual refcount against the expected. Thereby, the migration selftest fails on shared-anon mappings. The above enforces the fact that migration is a best-effort service, therefore, it is wrong to fail the test for just a single failure; hence, fail the test after 100 consecutive failures (where 100 is still a subjective choice). Note that, this has no effect on the execution time of the test since that is controlled by a timeout. [1] https://lore.kernel.org/all/20240801081657.1386743-1-dev.jain@arm.com/ Link: https://lkml.kernel.org/r/20240830051609.4037834-1-dev.jain@arm.com Signed-off-by: Dev Jain <dev.jain@arm.com> Suggested-by: David Hildenbrand <david@redhat.com> Reviewed-by: Ryan Roberts <ryan.roberts@arm.com> Tested-by: Ryan Roberts <ryan.roberts@arm.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Aneesh Kumar K.V <aneesh.kumar@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: Barry Song <baohua@kernel.org> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christoph Lameter <cl@gentwo.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Gavin Shan <gshan@redhat.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Lance Yang <ioworker0@gmail.com> Cc: Mark Brown <broonie@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: Shuah Khan <shuah@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Will Deacon <will@kernel.org> Cc: Yang Shi <yang@os.amperecomputing.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>