Re: [PATCH RT] mm/slub: close possible memory-leak in kmem_cache_alloc_bulk()
From: Jesper Dangaard Brouer <hidden>
Date: 2017-12-13 14:47:07
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linux-mm, lkml
On Wed, 13 Dec 2017 15:05:55 +0100 Sebastian Andrzej Siewior [off-list ref] wrote:
Under certain circumstances we could leak elements which were moved to the local "to_free" list. The damage is limited since I can't find any users here. Cc: stable-rt@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- Jesper: There are no users of kmem_cache_alloc_bulk() and kfree_bulk(). Only kmem_cache_free_bulk() is used since it was introduced. Do you think that it would make sense to remove those?
I would like to keep them. Rao Shoaib (Cc'ed) is/was working on a patchset for RCU-bulk-free that used the kfree_bulk() API. I plan to use kmem_cache_alloc_bulk() in the bpf-map "cpumap", for bulk allocating SKBs during dequeue of XDP frames. (My original bulk alloc SKBs use-case during NAPI/softirq was never merged).
quoted hunk ↗ jump to hunk
mm/slub.c | 1 + 1 file changed, 1 insertion(+)diff --git a/mm/slub.c b/mm/slub.c index ffd2fa0f415e..9053e929ce9d 100644 --- a/mm/slub.c +++ b/mm/slub.c@@ -3240,6 +3240,7 @@ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, return i; error: local_irq_enable(); + free_delayed(&to_free); slab_post_alloc_hook(s, flags, i, p); __kmem_cache_free_bulk(s, i, p); return 0;
I've not seen free_delayed() before... and my cscope cannot find it... -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>