Messages in this thread | | | Date | Mon, 25 Jul 2022 20:50:38 +0900 | From | asmadeus@codewrec ... | Subject | Re: [syzbot] WARNING in p9_client_destroy |
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Vlastimil Babka wrote on Mon, Jul 25, 2022 at 12:15:24PM +0200: > On 7/24/22 15:17, syzbot wrote: > > syzbot has bisected this issue to: > > > > commit 7302e91f39a81a9c2efcf4bc5749d18128366945 > > Author: Marco Elver <elver@google.com> > > Date: Fri Jan 14 22:03:58 2022 +0000 > > > > mm/slab_common: use WARN() if cache still has objects on destroy > > Just to state the obvious, bisection pointed to a commit that added the > warning, but the reason for the warning would be that p9 is destroying a > kmem_cache without freeing all the objects there first, and that would be > true even before the commit.
Probably true from the moment that cache/idr was introduced... I've got a couple of fixes in next but given syzcaller claims that's the tree it was produced on I guess there can be more such leaks. (well, the lines it sent in the backtrace yesterday don't match next, but I wouldn't count on it)
If someone wants to have a look please feel free, I would bet the problem is just that p9_fd_close() doesn't call or does something equivalent to p9_conn_cancel() and there just are some requests that haven't been sent yet when the mount is closed.. But I don't have/can/want to take the time to check right now as I consider such a leak harmless enough, someone has to be root or equivalent to do 9p mounts in most cases.
-- Dominique
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