Date: Wed, 6 Dec 2000 12:50:59 -0800 (PST) From: Matt Dillon <dillon@earth.backplane.com> To: stable@freebsd.org Cc: Barry Lustig <barry@lustig.com> Subject: Re: VMware hanging Message-ID: <200012062050.eB6Koxc98287@earth.backplane.com>
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Ok (this to the -stable mailing list). Barry and I have figurd out
why VMWare was locking up on him.
We tracked it down to excessive dirty filesystem buffers, created
through this codepath:
Debugger(c02ca083) at Debugger+0x35
panic(c02cd684,ca77cbe8,c018054a,c4f9cdb8,c4f9cdb8) at panic+0x70
bdirty(c4f9cdb8,c4f9cdb8,cb719000,0,c1218800) at bdirty+0x5d
bdwrite(c4f9cdb8,cb719000,0,0,2000) at bdwrite+0x52
cluster_write(c4f9cdb8,676a000,0,0) at cluster_write+0x313
ffs_write(ca77ccf8) at ffs_write+0x48b
vnode_pager_generic_putpages(cb719000,ca77ce08,10000,0,ca77cd9c) at
vnode_pager_generic_putpages+0x181
ffs_putpages(ca77cd60) at ffs_putpages+0x1f
vnode_pager_putpages(cb72dae0,ca77ce08,10,0,ca77cd9c) at vnode_pager_putpages+0x
6a
vm_pageout_flush(ca77ce08,10,0,0,c0ad7a7c) at vm_pageout_flush+0xb1
vm_object_page_clean(cb72dae0,0,0,4,0) at vm_object_page_clean+0x36a
vfs_msync(c11e5200,2,ca768600,0,ca76e780) at vfs_msync+0xc5
sync_fsync(ca77cf7c) at sync_fsync+0x4b
sched_sync(0) at sched_sync+0xf3
fork_trampoline() at fork_trampoline+0x8
The problem occurs when msync() tries to flush non-contiguous dirty
pages. There is a hole in cluster code that does not check for
excessive dirty buffers before issuing a bdwrite(), resulting in
excessive dirty buffers. Since the cluster code is rather sensitive,
my fix occurs at a higher level (in the UFS code).
The patch below appears to solve the problem for Barry. I will commit
it to -current now, and to -stable in 2 days. I've also committed a
patch to writev() to -current and will backport it to -stable in 2 days
as well.
-Matt
Index: ufs/ufs/ufs_readwrite.c
===================================================================
RCS file: /home/ncvs/src/sys/ufs/ufs/ufs_readwrite.c,v
retrieving revision 1.65.2.3
diff -u -r1.65.2.3 ufs_readwrite.c
--- ufs/ufs/ufs_readwrite.c 2000/11/26 02:55:13 1.65.2.3
+++ ufs/ufs/ufs_readwrite.c 2000/12/06 20:03:59
@@ -495,6 +495,9 @@
if (ioflag & IO_SYNC) {
(void)bwrite(bp);
+ } else if (vm_page_count_severe() || buf_dirty_count_severe()) {
+ bp->b_flags |= B_CLUSTEROK;
+ bawrite(bp);
} else if (xfersize + blkoffset == fs->fs_bsize) {
if ((vp->v_mount->mnt_flag & MNT_NOCLUSTERW) == 0) {
bp->b_flags |= B_CLUSTEROK;
@@ -502,9 +505,6 @@
} else {
bawrite(bp);
}
- } else if (vm_page_count_severe() || buf_dirty_count_severe()) {
- bp->b_flags |= B_CLUSTEROK;
- bawrite(bp);
} else {
bp->b_flags |= B_CLUSTEROK;
bdwrite(bp);
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