NeilBrown 2973d8229b 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>
2023-02-02 22:33:13 -08:00
..
2022-05-09 17:20:37 -07:00
2021-07-08 11:48:20 -07:00
2022-12-13 10:43:59 -08:00
2022-10-24 12:12:32 -07:00
2021-05-06 19:24:12 -07:00
2022-09-26 12:19:12 -07:00
2018-08-16 12:14:42 -07:00
2021-01-21 14:06:00 -07:00
2022-03-07 12:48:35 -07:00
2021-08-19 09:02:55 +09:00
2022-12-12 17:28:58 -08:00
2022-09-01 18:04:43 +02:00
2022-04-22 21:30:57 +02:00
2021-01-03 20:05:18 -05:00
2022-03-07 12:48:35 -07:00
2022-04-29 14:38:01 -07:00
2022-07-10 13:55:49 -07:00
2022-10-03 14:03:21 -07:00
2022-12-13 10:43:59 -08:00
2021-08-19 09:02:55 +09:00
2022-12-14 09:15:43 -08:00
2022-12-13 19:29:45 -08:00
2021-07-08 11:48:20 -07:00
2022-12-16 03:54:54 -08:00
2021-07-08 11:48:20 -07:00
2022-12-14 12:20:00 -08:00
2018-10-16 13:45:44 +02:00
2022-12-14 12:20:00 -08:00
2022-11-08 15:06:56 -08:00
2022-10-03 17:34:32 -07:00
2021-07-08 11:48:20 -07:00
2022-12-13 10:43:59 -08:00
2021-07-08 11:48:20 -07:00
2022-06-03 10:34:34 -07:00
2021-06-18 11:43:09 +02:00
2021-07-08 11:48:20 -07:00
2022-11-11 18:18:05 -08:00
2022-01-20 08:52:54 +02:00
2018-10-15 16:31:29 -04:00
2023-02-02 22:33:13 -08:00
2022-12-13 15:47:48 -08:00