diff options
| author | Mel Gorman <mgorman@techsingularity.net> | 2023-01-13 12:12:12 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-02-03 07:33:11 +0100 |
| commit | 524c48072e5673f4511f1ad81493e2485863fd65 (patch) | |
| tree | ead35272ae696995922d2c5325c71cc0ef3c31f1 /mm/internal.h | |
| parent | mm/page_ext: do not allocate space for page_ext->flags if not needed (diff) | |
| download | linux-524c48072e5673f4511f1ad81493e2485863fd65.tar.xz linux-524c48072e5673f4511f1ad81493e2485863fd65.zip | |
mm/page_alloc: rename ALLOC_HIGH to ALLOC_MIN_RESERVE
Patch series "Discard __GFP_ATOMIC", v3.
Neil's patch has been residing in mm-unstable as commit 2fafb4fe8f7a ("mm:
discard __GFP_ATOMIC") for a long time and recently brought up again.
Most recently, I was worried that __GFP_HIGH allocations could use
high-order atomic reserves which is unintentional but there was no
response so lets revisit -- this series reworks how min reserves are used,
protects highorder reserves and then finishes with Neil's patch with very
minor modifications so it fits on top.
There was a review discussion on renaming __GFP_DIRECT_RECLAIM to
__GFP_ALLOW_BLOCKING but I didn't think it was that big an issue and is
orthogonal to the removal of __GFP_ATOMIC.
There were some concerns about how the gfp flags affect the min reserves
but it never reached a solid conclusion so I made my own attempt.
The series tries to iron out some of the details on how reserves are used.
ALLOC_HIGH becomes ALLOC_MIN_RESERVE and ALLOC_HARDER becomes
ALLOC_NON_BLOCK and documents how the reserves are affected. For example,
ALLOC_NON_BLOCK (no direct reclaim) on its own allows 25% of the min
reserve. ALLOC_MIN_RESERVE (__GFP_HIGH) allows 50% and both combined
allows deeper access again. ALLOC_OOM allows access to 75%.
High-order atomic allocations are explicitly handled with the caveat that
no __GFP_ATOMIC flag means that any high-order allocation that specifies
GFP_HIGH and cannot enter direct reclaim will be treated as if it was
GFP_ATOMIC.
This patch (of 6):
__GFP_HIGH aliases to ALLOC_HIGH but the name does not really hint what it
means. As ALLOC_HIGH is internal to the allocator, rename it to
ALLOC_MIN_RESERVE to document that the min reserves can be depleted.
Link: https://lkml.kernel.org/r/20230113111217.14134-1-mgorman@techsingularity.net
Link: https://lkml.kernel.org/r/20230113111217.14134-2-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>
Diffstat (limited to 'mm/internal.h')
| -rw-r--r-- | mm/internal.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/mm/internal.h b/mm/internal.h index 973b48e8b1af..99eb544fbded 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -779,7 +779,9 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone, #endif #define ALLOC_HARDER 0x10 /* try to alloc harder */ -#define ALLOC_HIGH 0x20 /* __GFP_HIGH set */ +#define ALLOC_MIN_RESERVE 0x20 /* __GFP_HIGH set. Allow access to 50% + * of the min watermark. + */ #define ALLOC_CPUSET 0x40 /* check for correct cpuset */ #define ALLOC_CMA 0x80 /* allow allocations from CMA areas */ #ifdef CONFIG_ZONE_DMA32 |