From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Ricardo Leitner Date: Sat, 23 Jul 2016 13:26:00 +0000 Subject: Re: [PATCH] net/sctp: terminate rhashtable walk correctly Message-Id: <20160723132600.GF9950@localhost.localdomain> List-Id: References: <1469259755-18079-1-git-send-email-vegard.nossum@oracle.com> In-Reply-To: <1469259755-18079-1-git-send-email-vegard.nossum@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Vegard Nossum Cc: Vlad Yasevich , Neil Horman , linux-sctp@vger.kernel.org, "David S. Miller" , netdev@vger.kernel.org, Xin Long , Herbert Xu , stable@vger.kernel.org On Sat, Jul 23, 2016 at 09:42:35AM +0200, Vegard Nossum wrote: > I was seeing a lot of these: > > BUG: sleeping function called from invalid context at mm/slab.h:388 > in_atomic(): 0, irqs_disabled(): 0, pid: 14971, name: trinity-c2 > Preemption disabled at:[] rhashtable_walk_start+0x46/0x150 > > [] preempt_count_add+0x1fb/0x280 > [] _raw_spin_lock+0x12/0x40 > [] console_unlock+0x2f7/0x930 > [] vprintk_emit+0x2fb/0x520 > [] vprintk_default+0x1a/0x20 > [] printk+0x94/0xb0 > [] print_stack_trace+0xe0/0x170 > [] ___might_sleep+0x3be/0x460 > [] __might_sleep+0x90/0x1a0 > [] kmem_cache_alloc+0x153/0x1e0 > [] rhashtable_walk_init+0xfe/0x2d0 > [] sctp_transport_walk_start+0x1e/0x60 > [] sctp_transport_seq_start+0x4d/0x150 > [] seq_read+0x27b/0x1180 > [] proc_reg_read+0xbc/0x180 > [] __vfs_read+0xdb/0x610 > [] vfs_read+0xea/0x2d0 > [] SyS_pread64+0x11b/0x150 > [] do_syscall_64+0x19c/0x410 > [] return_from_SYSCALL_64+0x0/0x6a > [] 0xffffffffffffffff > > Apparently we always need to call rhashtable_walk_stop(), even when > rhashtable_walk_start() fails: > > * rhashtable_walk_start - Start a hash table walk > * @iter: Hash table iterator > * > * Start a hash table walk. Note that we take the RCU lock in all > * cases including when we return an error. So you must always call > * rhashtable_walk_stop to clean up. > > otherwise we never call rcu_read_unlock() and we get the splat above. > > See-also: 53fa1036 ("sctp: fix some rhashtable functions using in sctp proc/diag") > See-also: f2dba9c6 ("rhashtable: Introduce rhashtable_walk_*") > Cc: Xin Long > Cc: Herbert Xu > Cc: stable@vger.kernel.org > Signed-off-by: Vegard Nossum > --- > net/sctp/socket.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/net/sctp/socket.c b/net/sctp/socket.c > index 67154b8..7f5689a 100644 > --- a/net/sctp/socket.c > +++ b/net/sctp/socket.c > @@ -4301,6 +4301,7 @@ int sctp_transport_walk_start(struct rhashtable_iter *iter) > > err = rhashtable_walk_start(iter); > if (err && err != -EAGAIN) { > + rhashtable_walk_stop(iter); > rhashtable_walk_exit(iter); I was doubt now if we shouldn't just call sctp_transport_walk_stop() instead, but maybe it's good to keep the two apart, error handling from actual stop. I think this one deserves a Fixes tag because prior to 53fa1036 it was okay. Fixes: 53fa1036 ("sctp: fix some rhashtable functions using in sctp proc/diag") Acked-by: Marcelo Ricardo Leitner > return err; > } > -- > 1.9.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-sctp" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >