Re: [GIT PULL] xfs: CIL and log scalability improvements

On Fri, Jun 04, 2021 at 07:15:33PM -0700, Darrick J. Wong wrote:

On Fri, Jun 04, 2021 at 07:03:54PM -0700, Darrick J. Wong wrote:

quoted

On Fri, Jun 04, 2021 at 01:29:28PM +1000, Dave Chinner wrote:

quoted

Hi Darrick,

Can you please pull the CIL and log improvements from the tag listed
below?

I tried that and threw the series at fstests, which crashed all VMs with
the following null pointer dereference:

BUG: kernel NULL pointer dereference, address: 0000000000000000
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0 
Oops: 0000 [#1] PREEMPT SMP
CPU: 2 PID: 731060 Comm: mount Not tainted 5.13.0-rc4-djwx #rc4
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014
RIP: 0010:xlog_cil_init+0x2f7/0x370 [xfs]
Code: b4 7e a0 bf 1c 00 00 00 e8 c6 3b 8d e0 85 c0 78 0c c6 05 13 7f 12 00 01 e9 7b fd ff ff 4
2 48 c7 c6 f8 bf 7f a0 <48> 8b 39 e8 f0 24 04 00 31 ff b9 fc 05 00 00 48 c7 c2 d9 b3 7e a0
RSP: 0018:ffffc9000776bcd0 EFLAGS: 00010286
RAX: 00000000fffffff0 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 00000000fffffff0 RSI: ffffffffa07fbff8 RDI: 00000000ffffffff
RBP: ffff888004cf3c00 R08: ffffffffa078fb40 R09: 0000000000000000
R10: 000000000000000c R11: 0000000000000048 R12: ffff888052810000
R13: 0000607f81c0b0f8 R14: ffff888004a09c00 R15: ffff888004a09c00
FS:  00007fd2e4486840(0000) GS:ffff88807e000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 00000000528e5004 CR4: 00000000001706a0
Call Trace:
 xlog_alloc_log+0x51f/0x5f0 [xfs]
 xfs_log_mount+0x55/0x340 [xfs]
 xfs_mountfs+0x4e4/0x9f0 [xfs]
 xfs_fs_fill_super+0x4dd/0x7a0 [xfs]
 ? suffix_kstrtoint.constprop.0+0xe0/0xe0 [xfs]
 get_tree_bdev+0x175/0x280
 vfs_get_tree+0x1a/0x80
 ? capable+0x2f/0x50
 path_mount+0x6fb/0xa90
 __x64_sys_mount+0x103/0x140
 do_syscall_64+0x3a/0x70
 entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fd2e46e8dde
Code: 48 8b 0d b5 80 0c 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0
f 1e fa 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 82 80 0c 00 f7 d8 64 89 01 48

I'm pretty sure that's due to:

	if (!xlog_cil_pcp_init) {
		int	ret;

		ret = cpuhp_setup_state_nocalls(CPUHP_XFS_CIL_DEAD,
						"xfs/cil_pcp:dead", NULL,
						xlog_cil_pcp_dead);
		if (ret < 0) {
			xfs_warn(cil->xc_log->l_mp,
	"Failed to initialise CIL hotplug, error %d. XFS is non-functional.",
				ret);

Because we haven't set cil->xc_log yet.

And having now fixed that, I get tons of:

XFS (sda): Failed to initialise CIL hotplug, error -16. XFS is non-functional.
XFS: Assertion failed: 0, file: fs/xfs/xfs_log_cil.c, line: 1532
------------[ cut here ]------------
WARNING: CPU: 2 PID: 113983 at fs/xfs/xfs_message.c:112 assfail+0x3c/0x40 [xfs]
Modules linked in: xfs libcrc32c ip6t_REJECT nf_reject_ipv6 ipt_REJECT nf_reject_ipv4 xt_REDIR

EBUSY??

Can you attach your .config so I can try to reproduce this? I'm
guessing that it's an artifact of CONFIG_XFS=m or something else
being built as a module because I use monolothic kernels on my test
VMs and, obviously, haven't seen a single failure here...

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com