----- Original Message ----- > From: "Greg KH" <[email protected]> > To: "CAI Qian" <[email protected]> > Cc: [email protected], "Christoph Lameter" <[email protected]>, "Joonsoo > Kim" <[email protected]>, "Paul Hargrove" > <[email protected]> > Sent: Friday, February 1, 2013 8:49:00 PM > Subject: Re: [PATCH] slub: assign refcount for kmalloc_caches > > On Thu, Jan 24, 2013 at 10:50:09PM -0500, CAI Qian wrote: > > This is for stable-3.7.y only and this problem has already been > > solved > > in mainline through some slab/slub re-work which isn't suitable to > > backport here. See create_kmalloc_cache() in mm/slab_common.c > > there. > > > > commit cce89f4f6911286500cf7be0363f46c9b0a12ce0('Move kmem_cache > > refcounting to common code') moves some refcount manipulation code > > to > > common code. Unfortunately, it also removed refcount assignment for > > kmalloc_caches. So, kmalloc_caches's refcount is initially 0. > > This makes erroneous situation. > > > > Paul Hargrove report that when he create a 8-byte kmem_cache and > > destory it, he encounter below message. > > 'Objects remaining in kmalloc-8 on kmem_cache_close()' > > > > 8-byte kmem_cache merge with 8-byte kmalloc cache and refcount is > > increased by one. So, resulting refcount is 1. When destroy it, it > > hit > > refcount = 0, then kmem_cache_close() is executed and error message > > is > > printed. > > > > This patch assign initial refcount 1 to kmalloc_caches, so fix this > > erroneous situation. > > > > Cc: <[email protected]> # v3.7 > > Cc: Christoph Lameter <[email protected]> > > Reported-by: Paul Hargrove <[email protected]> > > Signed-off-by: Joonsoo Kim <[email protected]> > > Signed-off-by: CAI Qian <[email protected]> > > > > diff --git a/mm/slub.c b/mm/slub.c > > index a0d6984..321afab 100644 > > --- a/mm/slub.c > > +++ b/mm/slub.c > > @@ -3279,6 +3279,7 @@ static struct kmem_cache *__init > > create_kmalloc_cache(const char *name, > > if (kmem_cache_open(s, flags)) > > goto panic; > > > > + s->refcount = 1; > > list_add(&s->list, &slab_caches); > > return s; > > -- > > Your email client dropped the last line of the patch, so I had to > hand-edit it. > > Ugh, please fix your email client, again... Ah, thanks for fixing that, Greg. Thought it won't matter for the last empty line. Oh, well, I'll add that to my check-list.
Regards, CAI Qian > > greg k-h > -- > To unsubscribe from this list: send the line "unsubscribe stable" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
