From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 2CCA06B02C6 for ; Fri, 20 Aug 2010 01:45:38 -0400 (EDT) Date: Fri, 20 Aug 2010 13:45:33 +0800 From: Wu Fengguang Subject: Re: [PATCH] VM: kswapd should not do blocking memory allocations Message-ID: <20100820054533.GB11847@localhost> References: <1282158241.8540.85.camel@heimdal.trondhjem.org> <1282159872.8540.96.camel@heimdal.trondhjem.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1282159872.8540.96.camel@heimdal.trondhjem.org> Sender: owner-linux-mm@kvack.org To: Trond Myklebust Cc: Ram Pai , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org List-ID: > Hi Ram, > > I was seeing it on NFS until I put in the following kswapd-specific hack > into nfs_release_page(): > > /* Only do I/O if gfp is a superset of GFP_KERNEL */ > if (mapping && (gfp & GFP_KERNEL) == GFP_KERNEL) { > int how = FLUSH_SYNC; > > /* Don't let kswapd deadlock waiting for OOM RPC calls */ > if (current_is_kswapd()) > how = 0; So the patch can remove the above workaround together, and add comment that NFS exploits the gfp mask to avoid complex operations involving recursive memory allocation and hence deadlock? Thanks, Fengguang > nfs_commit_inode(mapping->host, how); > } > > Remove the 'if (current_is_kswapd())' line, and run an mmap() write > intensive workload, and it should hang pretty much every time. > > Cheers > Trond > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- 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: email@kvack.org