Trond Myklebust wrote:
On Thu, 2008-04-10 at 13:54 +0200, Frank van Maarseveen wrote:
FYI,
On Thu, Mar 20, 2008 at 01:57:16PM +0100, Frank van Maarseveen wrote:
On Thu, Mar 20, 2008 at 08:47:13AM -0400, Trond Myklebust wrote:
On Wed, 2008-03-19 at 10:49 +0100, Frank van Maarseveen wrote:
FYI,
2.6.24.3 wrote:
kernel BUG at fs/nfs/pagelist.c:82!
BUG_ON(PagePrivate(page));
invalid opcode: 0000 [#1] SMP
Modules linked in: vmnetfilter vmnet(P) vmmon(P) vmthrottle
In addition, there are some NFS patches for handling >16 groups and
selectively disabling attribute caching so its not a clean kernel.
Pid: 4575, comm: tail Tainted: P (2.6.24.3-x177 #1)
^^^^
EIP: 0060:[<c01fc084>] EFLAGS: 00010202 CPU: 1
EIP is at nfs_create_request+0xf4/0x100
EAX: 80000821 EBX: e31a5300 ECX: 00000000 EDX: c1f0712c
ESI: c1f0712c EDI: e31a5338 EBP: e56dfd90 ESP: e56dfd74
DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
Process tail (pid: 4575, ti=e56de000 task=d4b65500 task.ti=e56de000)
Stack: 00000000 f669ad20 cac3c168 e7330cb0 00000000 00000000 cac3c168 e56dfdc8
c01fded5 00000000 000000a4 039cffff 000000a4 c1f0712c cac3c168 e7330cb0
e56dfdb4 e56dfdb4 ffffff8c c1f0712c e7330cb0 e56dfdf0 c01fe8ce e56dfddc
Call Trace:
[<c010562a>] show_trace_log_lvl+0x1a/0x30
[<c01056fa>] show_stack_log_lvl+0x9a/0xc0
[<c01058a8>] show_registers+0xc8/0x1d0
[<c0105b1c>] die+0x10c/0x230
[<c0105cd1>] do_trap+0x91/0xd0
[<c0105f79>] do_invalid_op+0x89/0xa0
[<c05bba02>] error_code+0x72/0x80
[<c01fded5>] nfs_readpage_async+0xb5/0x1b0
[<c01fe8ce>] nfs_readpage+0xae/0x120
[<c0155268>] do_generic_mapping_read+0xe8/0x440
[<c01558b0>] generic_file_aio_read+0x160/0x190
[<c01f4fb7>] nfs_file_read+0x97/0xe0
[<c01795e7>] do_sync_read+0xc7/0x120
[<c01796c4>] vfs_read+0x84/0x130
[<c01799fd>] sys_read+0x3d/0x70
[<c0104292>] syscall_call+0x7/0xb
=======================
Code: 02 75 0a e8 4f dc 3b 00 e9 4a ff ff ff 83 c4 10 b8 00 fe ff ff 5b 5e 5f 5d c3 8b 56 0c e9 7a ff ff ff 0f 0b eb fe 90 0f 0b eb fe <0f> 0b eb fe 90 8d b4 26 00 00 00 00 55 89 e5 53 83 ec 04 89 c3
EIP: [<c01fc084>] nfs_create_request+0xf4/0x100 SS:ESP 0068:e56dfd74
---[ end trace 0ef921372ea6410b ]---
The machine is a quad Xeon with 4GB ram with CONFIG_HIGHMEM64G=y
Would that be on a file that was open for read and write, or is it
possible that some other process was writing to the same file? If so,
then it might be a bug in nfs_wb_page().
Yes, I'm quite sure it was a "tail -f" on a logfile which gets
continuously appended to by another process.. So, one process reads it
while another one writes to it through different descriptors/struct file.
The problem occurred again on a different box under exactly the same
userland conditions yielding exactly the same stack trace. Kernels are
identical but no vmware modules this time.
Just a quick question: how does your > 16 groups patch behave when it is
denied a write with an EACCES error? I've got a feeling that this may be
due to the page getting redirtied and the RPC call retried. If so, then
the following patch may help.
Cheers
Trond
--------------------------------------------------------------------------
From: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
Date: Fri, 11 Apr 2008 16:03:54 -0400
Subject: NFS: Fix nfs_wb_page() to always exit with an error or a clean page
It is possible for nfs_wb_page() to sometimes exit with 0 return value, yet
the page is left in a dirty state.
For instance in the case where the server rebooted, and the COMMIT request
failed, then all the previously "clean" pages which were cached by the
server, but were not guaranteed to have been writted out to disk,
have to be redirtied and resent to the server.
The fix is to have nfs_wb_page_priority() check that the page is clean
before it exits...
Is this a problem if the page is mmap'd into a process address
space which is constantly touching it?
Thanx...
ps
This fixes a condition that triggers the BUG_ON(PagePrivate(page)) in
nfs_create_request() when we're in the nfs_readpage() path.
Also eliminate a redundant BUG_ON(!PageLocked(page)) while we're at it. It
turns out that clear_page_dirty_for_io() has the exact same test.
Signed-off-by: Trond Myklebust <Trond.Myklebust@xxxxxxxxxx>
---
fs/nfs/write.c | 24 +++++++++++++-----------
1 files changed, 13 insertions(+), 11 deletions(-)
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index ce40cad..3a2e821 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -1493,18 +1493,20 @@ static int nfs_wb_page_priority(struct inode *inode, struct page *page,
};
int ret;
- BUG_ON(!PageLocked(page));
- if (clear_page_dirty_for_io(page)) {
- ret = nfs_writepage_locked(page, &wbc);
+ do {
+ if (clear_page_dirty_for_io(page)) {
+ ret = nfs_writepage_locked(page, &wbc);
+ if (ret < 0)
+ goto out_error;
+ } else if (!PagePrivate(page))
+ break;
+ ret = nfs_sync_mapping_wait(page->mapping, &wbc, how);
if (ret < 0)
- goto out;
- }
- if (!PagePrivate(page))
- return 0;
- ret = nfs_sync_mapping_wait(page->mapping, &wbc, how);
- if (ret >= 0)
- return 0;
-out:
+ goto out_error;
+ /* Is the test for PageDirty() really needed here? */
+ } while (PagePrivate(page) || PageDirty(page));
+ return 0;
+out_error:
__mark_inode_dirty(inode, I_DIRTY_PAGES);
return ret;
}
--
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