| Message ID | 20180511020943.10132-2-david@fromorbit.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On Fri, May 11, 2018 at 12:09:42PM +1000, Dave Chinner wrote: > From: Dave Chinner <dchinner@redhat.com> > > Similar to log_recovery_delay, this delay occurs between the VFS > superblock being initialised and the xfs_mount being fully > initialised. It also poisons the per-ag radix tree node so that it > can be used for triggering shrinker races during mount > such as the following: > > <run memory pressure workload in background> > > $ cat dirty-mount.sh > #! /bin/bash > > umount -f /dev/pmem0 > mkfs.xfs -f /dev/pmem0 > mount /dev/pmem0 /mnt/test > rm -f /mnt/test/foo > xfs_io -fxc "pwrite 0 4k" -c fsync -c "shutdown" /mnt/test/foo > umount /dev/pmem0 > > # let's crash it now! > echo 30 > /sys/fs/xfs/debug/mount_delay > mount /dev/pmem0 /mnt/test > echo 0 > /sys/fs/xfs/debug/mount_delay > umount /dev/pmem0 > $ sudo ./dirty-mount.sh > ..... > [ 60.378118] CPU: 3 PID: 3577 Comm: fs_mark Tainted: G D W 4.16.0-rc5-dgc #440 > [ 60.378120] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014 > [ 60.378124] RIP: 0010:radix_tree_next_chunk+0x76/0x320 > [ 60.378127] RSP: 0018:ffffc9000276f4f8 EFLAGS: 00010282 > [ 60.383670] RAX: a5a5a5a5a5a5a5a4 RBX: 0000000000000010 RCX: 000000000000001a > [ 60.385277] RDX: 0000000000000000 RSI: ffffc9000276f540 RDI: 0000000000000000 > [ 60.386554] RBP: 0000000000000000 R08: 0000000000000000 R09: a5a5a5a5a5a5a5a5 > [ 60.388194] R10: 0000000000000006 R11: 0000000000000001 R12: ffffc9000276f598 > [ 60.389288] R13: 0000000000000040 R14: 0000000000000228 R15: ffff880816cd6458 > [ 60.390827] FS: 00007f5c124b9740(0000) GS:ffff88083fc00000(0000) knlGS:0000000000000000 > [ 60.392253] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 60.393423] CR2: 00007f5c11bba0b8 CR3: 000000035580e001 CR4: 00000000000606e0 > [ 60.394519] Call Trace: > [ 60.395252] radix_tree_gang_lookup_tag+0xc4/0x130 > [ 60.395948] xfs_perag_get_tag+0x37/0xf0 > [ 60.396522] xfs_reclaim_inodes_count+0x32/0x40 > [ 60.397178] xfs_fs_nr_cached_objects+0x11/0x20 > [ 60.397837] super_cache_count+0x35/0xc0 > [ 60.399159] shrink_slab.part.66+0xb1/0x370 > [ 60.400194] shrink_node+0x7e/0x1a0 > [ 60.401058] try_to_free_pages+0x199/0x470 > [ 60.402081] __alloc_pages_slowpath+0x3a1/0xd20 > [ 60.403729] __alloc_pages_nodemask+0x1c3/0x200 > [ 60.404941] cache_grow_begin+0x20b/0x2e0 > [ 60.406164] fallback_alloc+0x160/0x200 > [ 60.407088] kmem_cache_alloc+0x111/0x4e0 > [ 60.408038] ? xfs_buf_rele+0x61/0x430 > [ 60.408925] kmem_zone_alloc+0x61/0xe0 > [ 60.409965] xfs_inode_alloc+0x24/0x1d0 > ..... > > > Signed-Off-By: Dave Chinner <dchinner@redhat.com> > Reviewed-by: Brian Foster <bfoster@redhat.com> Looks ok, will test... Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com> --D > --- > fs/xfs/xfs_globals.c | 1 + > fs/xfs/xfs_super.c | 11 +++++++++++ > fs/xfs/xfs_sysctl.h | 1 + > fs/xfs/xfs_sysfs.c | 31 +++++++++++++++++++++++++++++++ > 4 files changed, 44 insertions(+) > > diff --git a/fs/xfs/xfs_globals.c b/fs/xfs/xfs_globals.c > index 3e1cc3001bcb..fdde17a2333c 100644 > --- a/fs/xfs/xfs_globals.c > +++ b/fs/xfs/xfs_globals.c > @@ -47,6 +47,7 @@ xfs_param_t xfs_params = { > > struct xfs_globals xfs_globals = { > .log_recovery_delay = 0, /* no delay by default */ > + .mount_delay = 0, /* no delay by default */ > #ifdef XFS_ASSERT_FATAL > .bug_on_assert = true, /* assert failures BUG() */ > #else > diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c > index 5726ef496980..a523eaeb3f29 100644 > --- a/fs/xfs/xfs_super.c > +++ b/fs/xfs/xfs_super.c > @@ -1635,6 +1635,17 @@ xfs_fs_fill_super( > #endif > sb->s_op = &xfs_super_operations; > > + /* > + * Delay mount work if the debug hook is set. This is debug > + * instrumention to coordinate simulation of xfs mount failures with > + * VFS superblock operations > + */ > + if (xfs_globals.mount_delay) { > + xfs_notice(mp, "Delaying mount for %d seconds.", > + xfs_globals.mount_delay); > + msleep(xfs_globals.mount_delay * 1000); > + } > + > if (silent) > flags |= XFS_MFSI_QUIET; > > diff --git a/fs/xfs/xfs_sysctl.h b/fs/xfs/xfs_sysctl.h > index 82afee005140..b53a33e69932 100644 > --- a/fs/xfs/xfs_sysctl.h > +++ b/fs/xfs/xfs_sysctl.h > @@ -95,6 +95,7 @@ extern xfs_param_t xfs_params; > > struct xfs_globals { > int log_recovery_delay; /* log recovery delay (secs) */ > + int mount_delay; /* mount setup delay (secs) */ > bool bug_on_assert; /* BUG() the kernel on assert failure */ > }; > extern struct xfs_globals xfs_globals; > diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c > index 8b2ccc234f36..2d5cd2529f8e 100644 > --- a/fs/xfs/xfs_sysfs.c > +++ b/fs/xfs/xfs_sysfs.c > @@ -165,9 +165,40 @@ log_recovery_delay_show( > } > XFS_SYSFS_ATTR_RW(log_recovery_delay); > > +STATIC ssize_t > +mount_delay_store( > + struct kobject *kobject, > + const char *buf, > + size_t count) > +{ > + int ret; > + int val; > + > + ret = kstrtoint(buf, 0, &val); > + if (ret) > + return ret; > + > + if (val < 0 || val > 60) > + return -EINVAL; > + > + xfs_globals.mount_delay = val; > + > + return count; > +} > + > +STATIC ssize_t > +mount_delay_show( > + struct kobject *kobject, > + char *buf) > +{ > + return snprintf(buf, PAGE_SIZE, "%d\n", xfs_globals.mount_delay); > +} > +XFS_SYSFS_ATTR_RW(mount_delay); > + > static struct attribute *xfs_dbg_attrs[] = { > ATTR_LIST(bug_on_assert), > ATTR_LIST(log_recovery_delay), > + ATTR_LIST(mount_delay), > NULL, > }; > > -- > 2.17.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-xfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/xfs/xfs_globals.c b/fs/xfs/xfs_globals.c index 3e1cc3001bcb..fdde17a2333c 100644 --- a/fs/xfs/xfs_globals.c +++ b/fs/xfs/xfs_globals.c @@ -47,6 +47,7 @@ xfs_param_t xfs_params = { struct xfs_globals xfs_globals = { .log_recovery_delay = 0, /* no delay by default */ + .mount_delay = 0, /* no delay by default */ #ifdef XFS_ASSERT_FATAL .bug_on_assert = true, /* assert failures BUG() */ #else diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c index 5726ef496980..a523eaeb3f29 100644 --- a/fs/xfs/xfs_super.c +++ b/fs/xfs/xfs_super.c @@ -1635,6 +1635,17 @@ xfs_fs_fill_super( #endif sb->s_op = &xfs_super_operations; + /* + * Delay mount work if the debug hook is set. This is debug + * instrumention to coordinate simulation of xfs mount failures with + * VFS superblock operations + */ + if (xfs_globals.mount_delay) { + xfs_notice(mp, "Delaying mount for %d seconds.", + xfs_globals.mount_delay); + msleep(xfs_globals.mount_delay * 1000); + } + if (silent) flags |= XFS_MFSI_QUIET; diff --git a/fs/xfs/xfs_sysctl.h b/fs/xfs/xfs_sysctl.h index 82afee005140..b53a33e69932 100644 --- a/fs/xfs/xfs_sysctl.h +++ b/fs/xfs/xfs_sysctl.h @@ -95,6 +95,7 @@ extern xfs_param_t xfs_params; struct xfs_globals { int log_recovery_delay; /* log recovery delay (secs) */ + int mount_delay; /* mount setup delay (secs) */ bool bug_on_assert; /* BUG() the kernel on assert failure */ }; extern struct xfs_globals xfs_globals; diff --git a/fs/xfs/xfs_sysfs.c b/fs/xfs/xfs_sysfs.c index 8b2ccc234f36..2d5cd2529f8e 100644 --- a/fs/xfs/xfs_sysfs.c +++ b/fs/xfs/xfs_sysfs.c @@ -165,9 +165,40 @@ log_recovery_delay_show( } XFS_SYSFS_ATTR_RW(log_recovery_delay); +STATIC ssize_t +mount_delay_store( + struct kobject *kobject, + const char *buf, + size_t count) +{ + int ret; + int val; + + ret = kstrtoint(buf, 0, &val); + if (ret) + return ret; + + if (val < 0 || val > 60) + return -EINVAL; + + xfs_globals.mount_delay = val; + + return count; +} + +STATIC ssize_t +mount_delay_show( + struct kobject *kobject, + char *buf) +{ + return snprintf(buf, PAGE_SIZE, "%d\n", xfs_globals.mount_delay); +} +XFS_SYSFS_ATTR_RW(mount_delay); + static struct attribute *xfs_dbg_attrs[] = { ATTR_LIST(bug_on_assert), ATTR_LIST(log_recovery_delay), + ATTR_LIST(mount_delay), NULL, };