From 2973d8229b78d3f148e0c45916a1e8b237dc6167 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Fri, 13 Jan 2023 11:12:17 +0000 Subject: mm: discard __GFP_ATOMIC __GFP_ATOMIC serves little purpose. Its main effect is to set ALLOC_HARDER which adds a few little boosts to increase the chance of an allocation succeeding, one of which is to lower the water-mark at which it will succeed. It is *always* paired with __GFP_HIGH which sets ALLOC_HIGH which also adjusts this watermark. It is probable that other users of __GFP_HIGH should benefit from the other little bonuses that __GFP_ATOMIC gets. __GFP_ATOMIC also gives a warning if used with __GFP_DIRECT_RECLAIM. There is little point to this. We already get a might_sleep() warning if __GFP_DIRECT_RECLAIM is set. __GFP_ATOMIC allows the "watermark_boost" to be side-stepped. It is probable that testing ALLOC_HARDER is a better fit here. __GFP_ATOMIC is used by tegra-smmu.c to check if the allocation might sleep. This should test __GFP_DIRECT_RECLAIM instead. This patch: - removes __GFP_ATOMIC - allows __GFP_HIGH allocations to ignore watermark boosting as well as GFP_ATOMIC requests. - makes other adjustments as suggested by the above. The net result is not change to GFP_ATOMIC allocations. Other allocations that use __GFP_HIGH will benefit from a few different extra privileges. This affects: xen, dm, md, ntfs3 the vermillion frame buffer hibernation ksm swap all of which likely produce more benefit than cost if these selected allocation are more likely to succeed quickly. [mgorman: Minor adjustments to rework on top of a series] Link: https://lkml.kernel.org/r/163712397076.13692.4727608274002939094@noble.neil.brown.name Link: https://lkml.kernel.org/r/20230113111217.14134-7-mgorman@techsingularity.net Signed-off-by: NeilBrown Signed-off-by: Mel Gorman Acked-by: Vlastimil Babka Acked-by: Michal Hocko Cc: Matthew Wilcox Cc: Thierry Reding Signed-off-by: Andrew Morton --- include/trace/events/mmflags.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/trace') diff --git a/include/trace/events/mmflags.h b/include/trace/events/mmflags.h index 412b5a46374c..9db52bc4ce19 100644 --- a/include/trace/events/mmflags.h +++ b/include/trace/events/mmflags.h @@ -31,7 +31,6 @@ gfpflag_string(__GFP_HIGHMEM), \ gfpflag_string(GFP_DMA32), \ gfpflag_string(__GFP_HIGH), \ - gfpflag_string(__GFP_ATOMIC), \ gfpflag_string(__GFP_IO), \ gfpflag_string(__GFP_FS), \ gfpflag_string(__GFP_NOWARN), \ -- cgit v1.2.3-70-g09d2