linux-kernel - [PATCH 07/12] mm, slab: ignore SLAB_RECLAIM_ACCOUNT with CONFIG_SLUB

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Message-Id: <20221121171202.22080-8-vbabka@suse.cz>
Date:   Mon, 21 Nov 2022 18:11:57 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Christoph Lameter <cl@...ux.com>,
        David Rientjes <rientjes@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Pekka Enberg <penberg@...nel.org>
Cc:     Hyeonggon Yoo <42.hyeyoo@...il.com>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Matthew Wilcox <willy@...radead.org>, patches@...ts.linux.dev,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Vlastimil Babka <vbabka@...e.cz>
Subject: [PATCH 07/12] mm, slab: ignore SLAB_RECLAIM_ACCOUNT with CONFIG_SLUB_TINY

SLAB_RECLAIM_ACCOUNT caches allocate their slab pages with
__GFP_RECLAIMABLE and can help against fragmentation by grouping pages
by mobility, but on tiny systems mobility grouping is likely disabled
anyway and ignoring SLAB_RECLAIM_ACCOUNT might instead lead to merging
of caches that are made incompatible just by the flag.

Thus with CONFIG_SLUB_TINY, make SLAB_RECLAIM_ACCOUNT ineffective.

Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
---
 include/linux/slab.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 3ce9474c90ab..1cbbda03ad06 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -129,7 +129,11 @@
 
 /* The following flags affect the page allocator grouping pages by mobility */
 /* Objects are reclaimable */
+#ifndef CONFIG_SLUB_TINY
 #define SLAB_RECLAIM_ACCOUNT	((slab_flags_t __force)0x00020000U)
+#else
+#define SLAB_RECLAIM_ACCOUNT	0
+#endif
 #define SLAB_TEMPORARY		SLAB_RECLAIM_ACCOUNT	/* Objects are short-lived */
 
 /*
-- 
2.38.1