---------- Forwarded message ----------
Date: Fri, 13 Feb 2015 15:17:40 +0000
From: Phillip Lougher <plougher@xxxxxxxxxx>
Reply-To: Red Hat INTERNAL-ONLY kernel discussion list
<rhkernel-list@xxxxxxxxxx>
To: rhkernel-list@xxxxxxxxxx
Cc: steved@xxxxxxxxxx, jlayton@xxxxxxxxxx, swhiteho@xxxxxxxxxx
Subject: [RHEL 6.2.z PATCH] [fs] nfs: skip commit in releasepage if we:re freeing
memory for fs-related reasons
BZ: https://bugzilla.redhat.com/show_bug.cgi?id=1192326
Brew: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=8732178
Backport of following Rhel-6.4 patch to Rhel-6.2.z.
This patch does not apply to 6.2.z because it is missing the
patch-set added in BZ 785823 (11 patches).
However, the patch is easy to backport because the failure is due to:
1. Attempting to patch functionality added in the above patch-set,
specifically xs_local_setup_socket()
This part of the patch has been discarded.
2. Patching two other functions (which are identical), but patch
fails to fuzz them due to the functions having moved
significantly in the file (again due to the above patch-set).
-------
Message-id: <1343730895-2575-1-git-send-email-jlayton@xxxxxxxxxx>
Patchwork-id: 49134
O-Subject: [RHEL6 PATCH] BZ#832434: nfs: skip commit in releasepage if we're freeing memory for fs-related reasons
Bugzilla: 832434
RH-Acked-by: Steve Dickson <SteveD@xxxxxxxxxx>
This patch is not yet in mainline, but is in Trond's tree and should
make its way to mainline soon. The bug is here:
https://bugzilla.redhat.com/show_bug.cgi?id=832434
...and the customer that reported it has been successfully testing a
backport of this patch to a 6.1.z kernel. The commit ID in Trond's
tree is 5cf02d09b50b1ee1c2d536c9cf64af5a7d433f56, but that could change
by the time it gets merged into mainline.
Upstream patch description follows:
----------------------[snip]-----------------------
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@xxxxxxxxxx>
Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Phillip Lougher <plougher@xxxxxxxxxx>
---
fs/nfs/file.c | 7 +++++--
net/sunrpc/sched.c | 2 ++
net/sunrpc/xprtrdma/transport.c | 3 ++-
net/sunrpc/xprtsock.c | 7 +++++++
4 files changed, 16 insertions(+), 3 deletions(-)
diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index 6b31b97..22644e0 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -488,8 +488,11 @@ 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 b981b4d..1328537 100644
--- a/net/sunrpc/sched.c
+++ b/net/sunrpc/sched.c
@@ -713,7 +713,9 @@ 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 538589a..e392d2f 100644
--- a/net/sunrpc/xprtrdma/transport.c
+++ b/net/sunrpc/xprtrdma/transport.c
@@ -216,6 +216,7 @@ 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__,
@@ -228,10 +229,10 @@ 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 45be736..7ca3070 100644
--- a/net/sunrpc/xprtsock.c
+++ b/net/sunrpc/xprtsock.c
@@ -1700,6 +1700,8 @@ 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,
@@ -1718,6 +1720,7 @@ 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;
}
/*
@@ -1843,6 +1846,8 @@ 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,
@@ -1892,6 +1897,7 @@ 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
@@ -1904,6 +1910,7 @@ out_eagain:
out:
xprt_clear_connecting(xprt);
xprt_wake_pending_tasks(xprt, status);
+ current->flags &= ~PF_FSTRANS;
}
/**
