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authorNeilBrown <neilb@suse.de>2023-01-13 14:12:17 +0300
committerAndrew Morton <akpm@linux-foundation.org>2023-02-03 09:33:13 +0300
commit2973d8229b78d3f148e0c45916a1e8b237dc6167 (patch)
treea791740a86d240df1cebf02f915e5aede7065ea4 /lib/test_printf.c
parent1ebbb21811b76c3b932959787f37985af36f62fa (diff)
downloadlinux-2973d8229b78d3f148e0c45916a1e8b237dc6167.tar.xz
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 <neilb@suse.de> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Thierry Reding <thierry.reding@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'lib/test_printf.c')
-rw-r--r--lib/test_printf.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/lib/test_printf.c b/lib/test_printf.c
index d34dc636b81c..46b4e6c414a3 100644
--- a/lib/test_printf.c
+++ b/lib/test_printf.c
@@ -674,17 +674,17 @@ flags(void)
gfp = GFP_ATOMIC|__GFP_DMA;
test("GFP_ATOMIC|GFP_DMA", "%pGg", &gfp);
- gfp = __GFP_ATOMIC;
- test("__GFP_ATOMIC", "%pGg", &gfp);
+ gfp = __GFP_HIGH;
+ test("__GFP_HIGH", "%pGg", &gfp);
/* Any flags not translated by the table should remain numeric */
gfp = ~__GFP_BITS_MASK;
snprintf(cmp_buffer, BUF_SIZE, "%#lx", (unsigned long) gfp);
test(cmp_buffer, "%pGg", &gfp);
- snprintf(cmp_buffer, BUF_SIZE, "__GFP_ATOMIC|%#lx",
+ snprintf(cmp_buffer, BUF_SIZE, "__GFP_HIGH|%#lx",
(unsigned long) gfp);
- gfp |= __GFP_ATOMIC;
+ gfp |= __GFP_HIGH;
test(cmp_buffer, "%pGg", &gfp);
kfree(cmp_buffer);