From mboxrd@z Thu Jan 1 00:00:00 1970 From: Trond Myklebust Subject: Re: [PATCH 10/12] NFS: Simplify nfs_wb_page() Date: Wed, 10 Mar 2010 14:31:22 -0500 Message-ID: <1268249482.3096.76.camel@localhost.localdomain> References: <20100125221544.16750.70574.stgit@localhost.localdomain> <20100125221545.16750.19154.stgit@localhost.localdomain> <16839.1268247109@jrobl> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT Cc: linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Wu Fengguang , Peter Zijlstra , Jan Kara , Steve Rago , Jens Axboe , Peter Staubach , Arjan van de Ven , Ingo Molnar , linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Christoph Hellwig , Al Viro To: "J. R. Okajima" Return-path: In-Reply-To: <16839.1268247109@jrobl> Sender: linux-nfs-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-fsdevel.vger.kernel.org On Thu, 2010-03-11 at 03:51 +0900, J. R. Okajima wrote: > > INFO: task kswapd0:305 blocked for more than 120 seconds. > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > kswapd0 D 0000000000000001 0 305 2 0x00000000 > ffff88001f21d4f0 0000000000000046 ffff88001fdea680 ffff88001f21c000 > ffff88001f21dfd8 ffff88001f21c000 ffff88001f21dfd8 ffff88001f21dfd8 > ffff88001fdea040 0000000000014c00 0000000000000001 ffff88001fdea040 > Call Trace: > [] io_schedule+0x4d/0x70 > [] sync_page+0x65/0xa0 > [] __wait_on_bit_lock+0x52/0xb0 > [] ? sync_page+0x0/0xa0 > [] __lock_page+0x64/0x70 > [] ? wake_bit_function+0x0/0x40 > [] truncate_inode_pages_range+0x344/0x4a0 > [] truncate_inode_pages+0x10/0x20 > [] generic_delete_inode+0x15e/0x190 > [] generic_drop_inode+0x5d/0x80 > [] iput+0x78/0x80 > [] nfs_dentry_iput+0x38/0x50 > [] dentry_iput+0x84/0x110 > [] d_kill+0x2e/0x60 > [] dput+0x7a/0x170 > [] path_put+0x15/0x40 > [] __put_nfs_open_context+0xa4/0xb0 > [] ? nfs_free_request+0x0/0x50 > [] put_nfs_open_context+0xb/0x10 > [] nfs_free_request+0x29/0x50 > [] kref_put+0x8e/0xe0 > [] nfs_release_request+0x14/0x20 > [] nfs_find_and_lock_request+0x89/0xa0 > [] nfs_wb_page+0x80/0x110 > [] nfs_release_page+0x70/0x90 > [] try_to_release_page+0x5e/0x80 > [] shrink_page_list+0x638/0x860 > [] shrink_zone+0x63e/0xc40 > [] ? _raw_spin_unlock+0x57/0x70 > [] ? up_read+0x1e/0x40 > [] kswapd+0x6c9/0xa20 > [] ? isolate_pages_global+0x0/0x280 > [] ? autoremove_wake_function+0x0/0x40 > [] ? kswapd+0x0/0xa20 > [] kthread+0x96/0xb0 > [] kernel_thread_helper+0x4/0x10 > [] ? restore_args+0x0/0x30 > [] ? kthread+0x0/0xb0 > [] ? kernel_thread_helper+0x0/0x10 > no locks held by kswapd0/305. > > > diff --git a/fs/nfs/file.c b/fs/nfs/file.c > index ae8d022..ffa5463 100644 > --- a/fs/nfs/file.c > +++ b/fs/nfs/file.c > @@ -491,8 +491,13 @@ static int nfs_release_page(struct page *page, gfp_t gfp) > { > dfprintk(PAGECACHE, "NFS: release_page(%p)\n", page); > > - if (gfp & __GFP_WAIT) > + if (gfp & __GFP_WAIT) { > + struct inode *inode; > + > + inode = igrab(page->mapping->host); > nfs_wb_page(page->mapping->host, page); > + iput(inode); > + } > /* If PagePrivate() is set, then the page is not freeable */ > if (PagePrivate(page)) > return 0; > > > J. R. Okajima >>From your trace it looks as if the problem is that the nfs_wb_page() is triggering a dentry release, which deadlocks with in truncate_inode_pages() because the _caller_ of nfs_release_page() holds a page lock. As far as I can see, your iput() call above can deadlock in exactly the same way. Note that shrink_page_list() is the only function that does this sort of thing without holding a reference to the inode. Cheers Trond -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html