diff options
| -rw-r--r-- | include/linux/gfp.h | 23 | ||||
| -rw-r--r-- | include/net/sock.h | 11 |
2 files changed, 31 insertions, 3 deletions
diff --git a/include/linux/gfp.h b/include/linux/gfp.h index fb07b503dc45..61f2f6ff9467 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -325,6 +325,29 @@ static inline bool gfpflags_allow_blocking(const gfp_t gfp_flags) return !!(gfp_flags & __GFP_DIRECT_RECLAIM); } +/** + * gfpflags_normal_context - is gfp_flags a normal sleepable context? + * @gfp_flags: gfp_flags to test + * + * Test whether @gfp_flags indicates that the allocation is from the + * %current context and allowed to sleep. + * + * An allocation being allowed to block doesn't mean it owns the %current + * context. When direct reclaim path tries to allocate memory, the + * allocation context is nested inside whatever %current was doing at the + * time of the original allocation. The nested allocation may be allowed + * to block but modifying anything %current owns can corrupt the outer + * context's expectations. + * + * %true result from this function indicates that the allocation context + * can sleep and use anything that's associated with %current. + */ +static inline bool gfpflags_normal_context(const gfp_t gfp_flags) +{ + return (gfp_flags & (__GFP_DIRECT_RECLAIM | __GFP_MEMALLOC)) == + __GFP_DIRECT_RECLAIM; +} + #ifdef CONFIG_HIGHMEM #define OPT_ZONE_HIGHMEM ZONE_HIGHMEM #else diff --git a/include/net/sock.h b/include/net/sock.h index f69b58bff7e5..c31a9ed86d5a 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -2242,12 +2242,17 @@ struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp, * sk_page_frag - return an appropriate page_frag * @sk: socket * - * If socket allocation mode allows current thread to sleep, it means its - * safe to use the per task page_frag instead of the per socket one. + * Use the per task page_frag instead of the per socket one for + * optimization when we know that we're in the normal context and owns + * everything that's associated with %current. + * + * gfpflags_allow_blocking() isn't enough here as direct reclaim may nest + * inside other socket operations and end up recursing into sk_page_frag() + * while it's already in use. */ static inline struct page_frag *sk_page_frag(struct sock *sk) { - if (gfpflags_allow_blocking(sk->sk_allocation)) + if (gfpflags_normal_context(sk->sk_allocation)) return ¤t->task_frag; return &sk->sk_frag; |