[026/163] mm, slab: check GFP_SLAB_BUG_MASK before alloc_pages in kmalloc_order

Commit Message

Andrew Morton Aug. 7, 2020, 6:18 a.m. UTC

From: Long Li <[e-mail]>
Subject: mm, slab: check GFP_SLAB_BUG_MASK before alloc_pages in kmalloc_order

kmalloc cannot allocate memory from HIGHMEM.  Allocating large amounts of
memory currently bypasses the check and will simply leak the memory when
page_address() returns NULL.  To fix this, factor the GFP_SLAB_BUG_MASK
check out of slab & slub, and call it from kmalloc_order() as well.  In
order to make the code clear, the warning message is put in one place.

Link: http://lkml.kernel.org/r/20200704035027.GA62481@lilong
Signed-off-by: Long Li <[e-mail]>
Reviewed-by: Matthew Wilcox (Oracle) <[e-mail]>
Reviewed-by: Pekka Enberg <[e-mail]>
Acked-by: David Rientjes <[e-mail]>
Cc: Christoph Lameter <[e-mail]>
Cc: Joonsoo Kim <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/slab.c        |   10 +++-------
 mm/slab.h        |    1 +
 mm/slab_common.c |   17 +++++++++++++++++
 mm/slub.c        |    9 ++-------
 4 files changed, 23 insertions(+), 14 deletions(-)

Patch

--- a/mm/slab.c~mm-slab-check-gfp_slab_bug_mask-before-alloc_pages-in-kmalloc_order
+++ a/mm/slab.c
@@ -2589,13 +2589,9 @@  static struct page *cache_grow_begin(str
 	 * Be lazy and only check for valid flags here,  keeping it out of the
 	 * critical path in kmem_cache_alloc().
 	 */
-	if (unlikely(flags & GFP_SLAB_BUG_MASK)) {
-		gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;
-		flags &= ~GFP_SLAB_BUG_MASK;
-		pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
-				invalid_mask, &invalid_mask, flags, &flags);
-		dump_stack();
-	}
+	if (unlikely(flags & GFP_SLAB_BUG_MASK))
+		flags = kmalloc_fix_flags(flags);
+
 	WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO));
 	local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);
 
--- a/mm/slab_common.c~mm-slab-check-gfp_slab_bug_mask-before-alloc_pages-in-kmalloc_order
+++ a/mm/slab_common.c
@@ -26,6 +26,8 @@ 
 #define CREATE_TRACE_POINTS
 #include <trace/events/kmem.h>
 
+#include "internal.h"
+
 #include "slab.h"
 
 enum slab_state slab_state;
@@ -1332,6 +1334,18 @@  void __init create_kmalloc_caches(slab_f
 }
 #endif /* !CONFIG_SLOB */
 
+gfp_t kmalloc_fix_flags(gfp_t flags)
+{
+	gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;
+
+	flags &= ~GFP_SLAB_BUG_MASK;
+	pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
+			invalid_mask, &invalid_mask, flags, &flags);
+	dump_stack();
+
+	return flags;
+}
+
 /*
  * To avoid unnecessary overhead, we pass through large allocation requests
  * directly to the page allocator. We use __GFP_COMP, because we will need to
@@ -1342,6 +1356,9 @@  void *kmalloc_order(size_t size, gfp_t f
 	void *ret = NULL;
 	struct page *page;
 
+	if (unlikely(flags & GFP_SLAB_BUG_MASK))
+		flags = kmalloc_fix_flags(flags);
+
 	flags |= __GFP_COMP;
 	page = alloc_pages(flags, order);
 	if (likely(page)) {
--- a/mm/slab.h~mm-slab-check-gfp_slab_bug_mask-before-alloc_pages-in-kmalloc_order
+++ a/mm/slab.h
@@ -152,6 +152,7 @@  void create_kmalloc_caches(slab_flags_t)
 struct kmem_cache *kmalloc_slab(size_t, gfp_t);
 #endif
 
+gfp_t kmalloc_fix_flags(gfp_t flags);
 
 /* Functions provided by the slab allocators */
 int __kmem_cache_create(struct kmem_cache *, slab_flags_t flags);
--- a/mm/slub.c~mm-slab-check-gfp_slab_bug_mask-before-alloc_pages-in-kmalloc_order
+++ a/mm/slub.c
@@ -1745,13 +1745,8 @@  out:
 
 static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
 {
-	if (unlikely(flags & GFP_SLAB_BUG_MASK)) {
-		gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;
-		flags &= ~GFP_SLAB_BUG_MASK;
-		pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
-				invalid_mask, &invalid_mask, flags, &flags);
-		dump_stack();
-	}
+	if (unlikely(flags & GFP_SLAB_BUG_MASK))
+		flags = kmalloc_fix_flags(flags);
 
 	return allocate_slab(s,
 		flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);