Attachment 597103 Details for Bug 834808 – patchset -- don't block in releasepage when recursing back from a fs transaction or memory allocation

[patch] patchset -- don't block in releasepage when recursing back from a fs transaction or memory allocation

nfs-dont-block-in-releasepage-when-allocating.patch (text/plain), 7.67 KB, created by Jeff Layton on 2012-07-09 16:10:24 UTC

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Creator: Jeff Layton

Created: 2012-07-09 16:10:24 UTC

Size: 7.67 KB

patch

obsolete

>-------------------------------------------------------------------------------
>nfs-do-non-blocking-commit-in-
>-------------------------------------------------------------------------------
>nfs: skip commit in releasepage if we're freeing memory for fs-related reasons
>
>From: Jeff Layton <jlayton@redhat.com>
>
>We've had some reports of a deadlock where rpciod ends up with a stack
>trace like this:
>
>    PID: 2507   TASK: ffff88103691ab40  CPU: 14  COMMAND: "rpciod/14"
>     #0 [ffff8810343bf2f0] schedule at ffffffff814dabd9
>     #1 [ffff8810343bf3b8] nfs_wait_bit_killable at ffffffffa038fc04 [nfs]
>     #2 [ffff8810343bf3c8] __wait_on_bit at ffffffff814dbc2f
>     #3 [ffff8810343bf418] out_of_line_wait_on_bit at ffffffff814dbcd8
>     #4 [ffff8810343bf488] nfs_commit_inode at ffffffffa039e0c1 [nfs]
>     #5 [ffff8810343bf4f8] nfs_release_page at ffffffffa038bef6 [nfs]
>     #6 [ffff8810343bf528] try_to_release_page at ffffffff8110c670
>     #7 [ffff8810343bf538] shrink_page_list.clone.0 at ffffffff81126271
>     #8 [ffff8810343bf668] shrink_inactive_list at ffffffff81126638
>     #9 [ffff8810343bf818] shrink_zone at ffffffff8112788f
>    #10 [ffff8810343bf8c8] do_try_to_free_pages at ffffffff81127b1e
>    #11 [ffff8810343bf958] try_to_free_pages at ffffffff8112812f
>    #12 [ffff8810343bfa08] __alloc_pages_nodemask at ffffffff8111fdad
>    #13 [ffff8810343bfb28] kmem_getpages at ffffffff81159942
>    #14 [ffff8810343bfb58] fallback_alloc at ffffffff8115a55a
>    #15 [ffff8810343bfbd8] ____cache_alloc_node at ffffffff8115a2d9
>    #16 [ffff8810343bfc38] kmem_cache_alloc at ffffffff8115b09b
>    #17 [ffff8810343bfc78] sk_prot_alloc at ffffffff81411808
>    #18 [ffff8810343bfcb8] sk_alloc at ffffffff8141197c
>    #19 [ffff8810343bfce8] inet_create at ffffffff81483ba6
>    #20 [ffff8810343bfd38] __sock_create at ffffffff8140b4a7
>    #21 [ffff8810343bfd98] xs_create_sock at ffffffffa01f649b [sunrpc]
>    #22 [ffff8810343bfdd8] xs_tcp_setup_socket at ffffffffa01f6965 [sunrpc]
>    #23 [ffff8810343bfe38] worker_thread at ffffffff810887d0
>    #24 [ffff8810343bfee8] kthread at ffffffff8108dd96
>    #25 [ffff8810343bff48] kernel_thread at ffffffff8100c1ca
>
>rpciod is trying to allocate memory for a new socket to talk to the
>server. The VM ends up calling ->releasepage to get more memory, and it
>tries to do a blocking commit. That commit can't succeed however without
>a connected socket, so we deadlock.
>
>Fix this by setting PF_FSTRANS on the workqueue task prior to doing the
>socket allocation, and having nfs_release_page check for that flag when
>deciding whether to do a commit call. Also, set PF_FSTRANS
>unconditionally in rpc_async_schedule since that function can also do
>allocations sometimes.
>
>Signed-off-by: Jeff Layton <jlayton@redhat.com>
>---
>
> fs/nfs/file.c                   |    7 +++++--
> net/sunrpc/sched.c              |    2 ++
> net/sunrpc/xprtrdma/transport.c |    3 ++-
> net/sunrpc/xprtsock.c           |   10 ++++++++++
> 4 files changed, 19 insertions(+), 3 deletions(-)
>
>
>diff --git a/fs/nfs/file.c b/fs/nfs/file.c
>index a6708e6b..9075769 100644
>--- a/fs/nfs/file.c
>+++ b/fs/nfs/file.c
>@@ -459,8 +459,11 @@ static int nfs_release_page(struct page *page, gfp_t gfp)
> 
> 	dfprintk(PAGECACHE, "NFS: release_page(%p)\n", page);
> 
>-	/* Only do I/O if gfp is a superset of GFP_KERNEL */
>-	if (mapping && (gfp & GFP_KERNEL) == GFP_KERNEL) {
>+	/* Only do I/O if gfp is a superset of GFP_KERNEL, and we're not
>+	 * doing this memory reclaim for a fs-related allocation.
>+	 */
>+	if (mapping && (gfp & GFP_KERNEL) == GFP_KERNEL &&
>+	    !(current->flags & PF_FSTRANS)) {
> 		int how = FLUSH_SYNC;
> 
> 		/* Don't let kswapd deadlock waiting for OOM RPC calls */
>diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c
>index 994cfea..eda32ae 100644
>--- a/net/sunrpc/sched.c
>+++ b/net/sunrpc/sched.c
>@@ -790,7 +790,9 @@ void rpc_execute(struct rpc_task *task)
> 
> static void rpc_async_schedule(struct work_struct *work)
> {
>+	current->flags |= PF_FSTRANS;
> 	__rpc_execute(container_of(work, struct rpc_task, u.tk_work));
>+	current->flags &= ~PF_FSTRANS;
> }
> 
> /**
>diff --git a/net/sunrpc/xprtrdma/transport.c b/net/sunrpc/xprtrdma/transport.c
>index b446e10..06cdbff 100644
>--- a/net/sunrpc/xprtrdma/transport.c
>+++ b/net/sunrpc/xprtrdma/transport.c
>@@ -200,6 +200,7 @@ xprt_rdma_connect_worker(struct work_struct *work)
> 	int rc = 0;
> 
> 	if (!xprt->shutdown) {
>+		current->flags |= PF_FSTRANS;
> 		xprt_clear_connected(xprt);
> 
> 		dprintk("RPC:       %s: %sconnect\n", __func__,
>@@ -212,10 +213,10 @@ xprt_rdma_connect_worker(struct work_struct *work)
> 
> out:
> 	xprt_wake_pending_tasks(xprt, rc);
>-
> out_clear:
> 	dprintk("RPC:       %s: exit\n", __func__);
> 	xprt_clear_connecting(xprt);
>+	current->flags &= ~PF_FSTRANS;
> }
> 
> /*
>diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c
>index 890b03f..b88c6bf 100644
>--- a/net/sunrpc/xprtsock.c
>+++ b/net/sunrpc/xprtsock.c
>@@ -1895,6 +1895,8 @@ static void xs_local_setup_socket(struct work_struct *work)
> 	if (xprt->shutdown)
> 		goto out;
> 
>+	current->flags |= PF_FSTRANS;
>+
> 	clear_bit(XPRT_CONNECTION_ABORT, &xprt->state);
> 	status = __sock_create(xprt->xprt_net, AF_LOCAL,
> 					SOCK_STREAM, 0, &sock, 1);
>@@ -1928,6 +1930,7 @@ static void xs_local_setup_socket(struct work_struct *work)
> out:
> 	xprt_clear_connecting(xprt);
> 	xprt_wake_pending_tasks(xprt, status);
>+	current->flags &= ~PF_FSTRANS;
> }
> 
> static void xs_udp_finish_connecting(struct rpc_xprt *xprt, struct socket *sock)
>@@ -1970,6 +1973,8 @@ static void xs_udp_setup_socket(struct work_struct *work)
> 	if (xprt->shutdown)
> 		goto out;
> 
>+	current->flags |= PF_FSTRANS;
>+
> 	/* Start by resetting any existing state */
> 	xs_reset_transport(transport);
> 	sock = xs_create_sock(xprt, transport,
>@@ -1988,6 +1993,7 @@ static void xs_udp_setup_socket(struct work_struct *work)
> out:
> 	xprt_clear_connecting(xprt);
> 	xprt_wake_pending_tasks(xprt, status);
>+	current->flags &= ~PF_FSTRANS;
> }
> 
> /*
>@@ -2113,6 +2119,8 @@ static void xs_tcp_setup_socket(struct work_struct *work)
> 	if (xprt->shutdown)
> 		goto out;
> 
>+	current->flags |= PF_FSTRANS;
>+
> 	if (!sock) {
> 		clear_bit(XPRT_CONNECTION_ABORT, &xprt->state);
> 		sock = xs_create_sock(xprt, transport,
>@@ -2162,6 +2170,7 @@ static void xs_tcp_setup_socket(struct work_struct *work)
> 	case -EINPROGRESS:
> 	case -EALREADY:
> 		xprt_clear_connecting(xprt);
>+		current->flags &= ~PF_FSTRANS;
> 		return;
> 	case -EINVAL:
> 		/* Happens, for instance, if the user specified a link
>@@ -2174,6 +2183,7 @@ out_eagain:
> out:
> 	xprt_clear_connecting(xprt);
> 	xprt_wake_pending_tasks(xprt, status);
>+	current->flags &= ~PF_FSTRANS;
> }
> 
> /**
>-------------------------------------------------------------------------------
>nfs-broaden-the-cases-where-we
>-------------------------------------------------------------------------------
>nfs: broaden the cases where we use a non-blocking commit in releasepage
>
>From: Jeff Layton <jlayton@redhat.com>
>
>Currently, we just do a non-blocking commit when called from kswapd, but
>that still gives us some cases where we end up blocking after recursing
>back into the filesystem. Instead, turn that check into a check for
>PF_MEMALLOC so that we never block when trying to free memory in order to
>satisfy an allocation.
>
>Signed-off-by: Jeff Layton <jlayton@redhat.com>
>---
>
> fs/nfs/file.c |    4 ++--
> 1 files changed, 2 insertions(+), 2 deletions(-)
>
>
>diff --git a/fs/nfs/file.c b/fs/nfs/file.c
>index 9075769..61d3670 100644
>--- a/fs/nfs/file.c
>+++ b/fs/nfs/file.c
>@@ -466,8 +466,8 @@ static int nfs_release_page(struct page *page, gfp_t gfp)
> 	    !(current->flags & PF_FSTRANS)) {
> 		int how = FLUSH_SYNC;
> 
>-		/* Don't let kswapd deadlock waiting for OOM RPC calls */
>-		if (current_is_kswapd())
>+		/* Don't block if we're freeing for a memory allocation */
>+		if (current->flags & PF_MEMALLOC)
> 			how = 0;
> 		nfs_commit_inode(mapping->host, how);
> 	}

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Attachments on bug 834808: 593938 | 597103