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| author | Mel Gorman <mgorman@techsingularity.net> | 2023-01-13 11:12:13 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-11-08 16:26:46 +0100 |
| commit | 0d968ced7330f89fff7fd56f61f3a4743bbcce3e (patch) | |
| tree | 87054ea6b5d60b72e669d0c66ee7a5f47224bf76 | |
| parent | 241398329abcdd672d6754f7dba98e71a0e4d7b5 (diff) | |
| download | linux-0d968ced7330f89fff7fd56f61f3a4743bbcce3e.tar.gz linux-0d968ced7330f89fff7fd56f61f3a4743bbcce3e.tar.bz2 linux-0d968ced7330f89fff7fd56f61f3a4743bbcce3e.zip | |
mm/page_alloc: treat RT tasks similar to __GFP_HIGH
[ Upstream commit c988dcbecf3fd5430921eaa3fe9054754f76d185 ]
RT tasks are allowed to dip below the min reserve but ALLOC_HARDER is
typically combined with ALLOC_MIN_RESERVE so RT tasks are a little
unusual. While there is some justification for allowing RT tasks access
to memory reserves, there is a strong chance that a RT task that is also
under memory pressure is at risk of missing deadlines anyway. Relax how
much reserves an RT task can access by treating it the same as __GFP_HIGH
allocations.
Note that in a future kernel release that the RT special casing will be
removed. Hard realtime tasks should be locking down resources in advance
and ensuring enough memory is available. Even a soft-realtime task like
audio or video live decoding which cannot jitter should be allocating both
memory and any disk space required up-front before the recording starts
instead of relying on reserves. At best, reserve access will only delay
the problem by a very short interval.
Link: https://lkml.kernel.org/r/20230113111217.14134-3-mgorman@techsingularity.net
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: NeilBrown <neilb@suse.de>
Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: 281dd25c1a01 ("mm/page_alloc: let GFP_ATOMIC order-0 allocs access highatomic reserves")
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | mm/page_alloc.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index f5b870780d3f..e78ab23eb174 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4854,7 +4854,7 @@ gfp_to_alloc_flags(gfp_t gfp_mask) */ alloc_flags &= ~ALLOC_CPUSET; } else if (unlikely(rt_task(current)) && in_task()) - alloc_flags |= ALLOC_HARDER; + alloc_flags |= ALLOC_MIN_RESERVE; alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, alloc_flags); |