mm/page_alloc: ensure kswapd doesn't accidentally go to sleep

Patch series "A few cleanup patches for mm", v2.

This series contains a few cleanup patches to remove the obsolete comments
and functions, use helper macro to improve readability and so on.  More
details can be found in the respective changelogs.

This patch (of 16):

If ALLOC_KSWAPD is set, wake_all_kswapds() will be called to ensure kswapd
doesn't accidentally go to sleep.  But when reserve_flags is set,
alloc_flags will be overwritten and ALLOC_KSWAPD is thus lost.  Preserve
the ALLOC_KSWAPD flag in alloc_flags to ensure kswapd won't go to sleep
accidentally.

Link: https://lkml.kernel.org/r/20220916072257.9639-1-linmiaohe@huawei.com
Link: https://lkml.kernel.org/r/20220916072257.9639-2-linmiaohe@huawei.com
Fixes: 9d64d568e71e ("mm: use alloc_flags to record if kswapd can wake")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c7e9451c69fc75498de2e297eb658dac024ea552..24caa11db8aeefe1a2c1e6b2863d193142d11e8d 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5156,7 +5156,8 @@ retry:
 
        reserve_flags = __gfp_pfmemalloc_flags(gfp_mask);
        if (reserve_flags)
-               alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, reserve_flags);
+               alloc_flags = gfp_to_alloc_flags_cma(gfp_mask, reserve_flags) |
+                                         (alloc_flags & ALLOC_KSWAPD);
 
        /*
         * Reset the nodemask and zonelist iterators if memory policies can be