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

Andrew Morton
2020-08-07T06:18:31Z

From: Long Li <lonuxli.64@gmail.com>
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 <lonuxli.64@gmail.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

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

--- 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);
_