linux-kernel - [PATCH v2 01/16] mm/page_alloc: ensure kswapd doesn't accidentally go to sleep

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Date:   Fri, 16 Sep 2022 15:22:42 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <akpm@...ux-foundation.org>, <david@...hat.com>,
        <osalvador@...e.de>, <anshuman.khandual@....com>
CC:     <willy@...radead.org>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <linmiaohe@...wei.com>
Subject: [PATCH v2 01/16] mm/page_alloc: ensure kswapd doesn't accidentally go to sleep

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.

Fixes: 0a79cdad5eb2 ("mm: use alloc_flags to record if kswapd can wake")
Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
Acked-by: David Hildenbrand <david@...hat.com>
Reviewed-by: Oscar Salvador <osalvador@...e.de>
---
 mm/page_alloc.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ef3f51c9815d..35e18514215a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5148,7 +5148,8 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 
 	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
-- 
2.23.0