Return-Path: Received: from fieldses.org ([173.255.197.46]:50808 "EHLO fieldses.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932127AbeEHQLa (ORCPT ); Tue, 8 May 2018 12:11:30 -0400 Date: Tue, 8 May 2018 12:11:30 -0400 From: "bfields@fieldses.org" To: Trond Myklebust Cc: "syzbot+4b98281f2401ab849f4b@syzkaller.appspotmail.com" , "syzkaller-bugs@googlegroups.com" , "anna.schumaker@netapp.com" , "davem@davemloft.net" , "linux-kernel@vger.kernel.org" , "linux-nfs@vger.kernel.org" , "jlayton@kernel.org" , "netdev@vger.kernel.org" Subject: Re: general protection fault in encode_rpcb_string Message-ID: <20180508161130.GC6151@fieldses.org> References: <20180417213308.GC18217@fieldses.org> <1524002074.63751.5.camel@hammer.space> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1524002074.63751.5.camel@hammer.space> Sender: linux-nfs-owner@vger.kernel.org List-ID: From: "J. Bruce Fields" Date: Tue, 8 May 2018 11:47:03 -0400 Subject: [PATCH 2/2] sunrpc: convert unnecessary GFP_ATOMIC to GFP_NOFS It's OK to sleep here, we just don't want to recurse into the filesystem as this writeout could be waiting on this. As a next step: the documentation for GFP_NOFS says "Please try to avoid using this flag directly and instead use memalloc_nofs_{save,restore} to mark the whole scope which cannot/shouldn't recurse into the FS layer with a short explanation why. All allocation requests will inherit GFP_NOFS implicitly." But I'm not sure where to do this. Should the workqueue could be arranging that for us in the case of workqueues created with WQ_MEM_RECLAIM? Reported-by: Trond Myklebust Signed-off-by: J. Bruce Fields --- net/sunrpc/rpcb_clnt.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) On Tue, Apr 17, 2018 at 09:54:36PM +0000, Trond Myklebust wrote: > Yes, and we can probably convert it, and the other GFP_ATOMIC > allocations in the rpcbind client to use GFP_NOFS in order to improve > reliability. diff --git a/net/sunrpc/rpcb_clnt.c b/net/sunrpc/rpcb_clnt.c index 82c120e51d64..576e84a1adee 100644 --- a/net/sunrpc/rpcb_clnt.c +++ b/net/sunrpc/rpcb_clnt.c @@ -752,7 +752,7 @@ void rpcb_getport_async(struct rpc_task *task) goto bailout_nofree; } - map = kzalloc(sizeof(struct rpcbind_args), GFP_ATOMIC); + map = kzalloc(sizeof(struct rpcbind_args), GFP_NOFS); if (!map) { status = -ENOMEM; dprintk("RPC: %5u %s: no memory available\n", @@ -770,7 +770,7 @@ void rpcb_getport_async(struct rpc_task *task) case RPCBVERS_4: case RPCBVERS_3: map->r_netid = xprt->address_strings[RPC_DISPLAY_NETID]; - map->r_addr = rpc_sockaddr2uaddr(sap, GFP_ATOMIC); + map->r_addr = rpc_sockaddr2uaddr(sap, GFP_NOFS); if (!map->r_addr) { status = -ENOMEM; dprintk("RPC: %5u %s: no memory available\n", -- 2.17.0