From: Michal Hocko <mhocko@xxxxxxxx> Subject: xfs: map KM_MAYFAIL to __GFP_RETRY_MAYFAIL KM_MAYFAIL didn't have any suitable GFP_FOO counterpart until recently so it relied on the default page allocator behavior for the given set of flags. This means that small allocations actually never failed. Now that we have __GFP_RETRY_MAYFAIL flag which works independently on the allocation request size we can map KM_MAYFAIL to it. The allocator will try as hard as it can to fulfill the request but fails eventually if the progress cannot be made. It does so without triggering the OOM killer which can be seen as an improvement because KM_MAYFAIL users should be able to deal with allocation failures. Link: http://lkml.kernel.org/r/20170623085345.11304-4-mhocko@xxxxxxxxxx Signed-off-by: Michal Hocko <mhocko@xxxxxxxx> Cc: Darrick J. Wong <darrick.wong@xxxxxxxxxx> Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx> Cc: Alex Belits <alex.belits@xxxxxxxxxx> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: David Daney <david.daney@xxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Cc: NeilBrown <neilb@xxxxxxxx> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/xfs/kmem.h | 10 ++++++++++ 1 file changed, 10 insertions(+) diff -puN fs/xfs/kmem.h~xfs-map-km_mayfail-to-__gfp_retry_mayfail fs/xfs/kmem.h --- a/fs/xfs/kmem.h~xfs-map-km_mayfail-to-__gfp_retry_mayfail +++ a/fs/xfs/kmem.h @@ -54,6 +54,16 @@ kmem_flags_convert(xfs_km_flags_t flags) lflags &= ~__GFP_FS; } + /* + * Default page/slab allocator behavior is to retry for ever + * for small allocations. We can override this behavior by using + * __GFP_RETRY_MAYFAIL which will tell the allocator to retry as long + * as it is feasible but rather fail than retry forever for all + * request sizes. + */ + if (flags & KM_MAYFAIL) + lflags |= __GFP_RETRY_MAYFAIL; + if (flags & KM_ZERO) lflags |= __GFP_ZERO; _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
