linux-hardening - [RFC PATCH 06/14] mm/slub: pass additional args to alloc_slab

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Date:   Fri, 15 Sep 2023 10:59:25 +0000
From:   Matteo Rizzo <matteorizzo@...gle.com>
To:     cl@...ux.com, penberg@...nel.org, rientjes@...gle.com,
        iamjoonsoo.kim@....com, akpm@...ux-foundation.org, vbabka@...e.cz,
        roman.gushchin@...ux.dev, 42.hyeyoo@...il.com,
        keescook@...omium.org, linux-kernel@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-mm@...ck.org,
        linux-hardening@...r.kernel.org, tglx@...utronix.de,
        mingo@...hat.com, bp@...en8.de, dave.hansen@...ux.intel.com,
        x86@...nel.org, hpa@...or.com, corbet@....net, luto@...nel.org,
        peterz@...radead.org
Cc:     jannh@...gle.com, matteorizzo@...gle.com, evn@...gle.com,
        poprdi@...gle.com, jordyzomer@...gle.com
Subject: [RFC PATCH 06/14] mm/slub: pass additional args to alloc_slab_page

From: Jann Horn <jannh@...gle.com>

This is refactoring in preparation for SLAB_VIRTUAL.

The implementation of SLAB_VIRTUAL needs access to struct kmem_cache in
alloc_slab_page in order to take unused slabs from the slab freelist,
which is per-cache.

In addition to that it passes two different sets of GFP flags.
meta_gfp_flags is used for the memory backing the metadata region and
page tables, and gfp_flags for the data memory.

Signed-off-by: Jann Horn <jannh@...gle.com>
Co-developed-by: Matteo Rizzo <matteorizzo@...gle.com>
Signed-off-by: Matteo Rizzo <matteorizzo@...gle.com>
---
 mm/slub.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 9b87afade125..eaa1256aff89 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1869,7 +1869,8 @@ static void folio_clear_slab(struct folio *folio, struct slab *slab)
 	__folio_clear_slab(folio);
 }
 
-static inline struct slab *alloc_slab_page(gfp_t flags, int node,
+static inline struct slab *alloc_slab_page(struct kmem_cache *s,
+		gfp_t meta_flags, gfp_t flags, int node,
 		struct kmem_cache_order_objects oo)
 {
 	struct folio *folio;
@@ -2020,7 +2021,7 @@ static struct slab *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
 	if ((alloc_gfp & __GFP_DIRECT_RECLAIM) && oo_order(oo) > oo_order(s->min))
 		alloc_gfp = (alloc_gfp | __GFP_NOMEMALLOC) & ~__GFP_RECLAIM;
 
-	slab = alloc_slab_page(alloc_gfp, node, oo);
+	slab = alloc_slab_page(s, flags, alloc_gfp, node, oo);
 	if (unlikely(!slab)) {
 		oo = s->min;
 		alloc_gfp = flags;
@@ -2028,7 +2029,7 @@ static struct slab *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
 		 * Allocation may have failed due to fragmentation.
 		 * Try a lower order alloc if possible
 		 */
-		slab = alloc_slab_page(alloc_gfp, node, oo);
+		slab = alloc_slab_page(s, flags, alloc_gfp, node, oo);
 		if (unlikely(!slab))
 			return NULL;
 		stat(s, ORDER_FALLBACK);
-- 
2.42.0.459.ge4e396fd5e-goog