On Fri, Jun 04, 2021 at 01:29:28PM +1000, Dave Chinner wrote:
> 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.
--D
>
> Cheers,
>
> Dave.
>
> The following changes since commit d07f6ca923ea0927a1024dfccafc5b53b61cfecc:
>
> Linux 5.13-rc2 (2021-05-16 15:27:44 -0700)
>
> are available in the Git repository at:
>
> git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs.git tags/xfs-cil-scale-tag
>
> for you to fetch changes up to 856d6346ad5e76f230906792b1eb4ba70c860748:
>
> xfs: expanding delayed logging design with background material (2021-06-04 12:42:29 +1000)
>
> ----------------------------------------------------------------
> xfs: CIL and log scalability improvements
>
> Performance improvements are largely documented in the change logs of the
> individual patches. Headline numbers are an increase in transaction rate from
> 700k commits/s to 1.7M commits/s, and a reduction in fua/flush operations by
> 2-3 orders of magnitude on metadata heavy workloads that don't use fsync.
>
> Summary of series:
>
> Patches Modifications
> ------- -------------
> 1-7: log write FUA/FLUSH optimisations
> 8: bug fix
> 9-11: Async CIL pushes
> 12-25: xlog_write() rework
> 26-39: CIL commit scalability
>
> The log write FUA/FLUSH optimisations reduce the number of cache flushes
> required to flush the CIL to the journal. It extends the old pre-delayed logging
> ordering semantics required by writing individual transactions to the iclogs out
> to cover then CIL checkpoint transactions rather than individual writes to the
> iclogs. In doing so, we reduce the cache flush requirements to once per CIL
> checkpoint rather than once per iclog write.
>
> The async CIL pushes fix a pipeline limitation that only allowed a single CIL
> push to be processed at a time. This was causing CIL checkpoint writing to
> become CPU bound as only a single CIL checkpoint could be pushed at a time. The
> checkpoint pipleine was designed to allow multiple pushes to be in flight at
> once and use careful ordering of the commit records to ensure correct recovery
> order, but the workqueue implementation didn't allow concurrent works to be run.
> The concurrent works now extend out to 4 CIL checkpoints running at a time,
> hence removing the CPU usage limiations without introducing new lock contention
> issues.
>
> The xlog_write() rework is long overdue. The code is complex, difficult to
> understand, full of tricky, subtle corner cases and just generally really hard
> to modify. This patchset reworks the xlog_write() API to reduce the processing
> overhead of writing out long log vector chains, and factors the xlog_write()
> code into a simple, compact fast path along with a clearer slow path to handle
> the complex cases.
>
> The CIL commit scalability patchset removes spinlocks from the transaction
> commit fast path. These spinlocks are the performance limiting bottleneck in the
> transaction commit path, so we apply a variety of different techniques to do
> either atomic. lockless or per-cpu updates of the CIL tracking structures during
> commits. This greatly increases the throughput of the the transaction commit
> engine, moving the contention point to the log space tracking algorithms after
> doubling throughput on 32-way workloads.
>
> ----------------------------------------------------------------
> Dave Chinner (39):
> xfs: log stripe roundoff is a property of the log
> xfs: separate CIL commit record IO
> xfs: remove xfs_blkdev_issue_flush
> xfs: async blkdev cache flush
> xfs: CIL checkpoint flushes caches unconditionally
> xfs: remove need_start_rec parameter from xlog_write()
> xfs: journal IO cache flush reductions
> xfs: Fix CIL throttle hang when CIL space used going backwards
> xfs: xfs_log_force_lsn isn't passed a LSN
> xfs: AIL needs asynchronous CIL forcing
> xfs: CIL work is serialised, not pipelined
> xfs: factor out the CIL transaction header building
> xfs: only CIL pushes require a start record
> xfs: embed the xlog_op_header in the unmount record
> xfs: embed the xlog_op_header in the commit record
> xfs: log tickets don't need log client id
> xfs: move log iovec alignment to preparation function
> xfs: reserve space and initialise xlog_op_header in item formatting
> xfs: log ticket region debug is largely useless
> xfs: pass lv chain length into xlog_write()
> xfs: introduce xlog_write_single()
> xfs:_introduce xlog_write_partial()
> xfs: xlog_write() no longer needs contwr state
> xfs: xlog_write() doesn't need optype anymore
> xfs: CIL context doesn't need to count iovecs
> xfs: use the CIL space used counter for emptiness checks
> xfs: lift init CIL reservation out of xc_cil_lock
> xfs: rework per-iclog header CIL reservation
> xfs: introduce per-cpu CIL tracking structure
> xfs: implement percpu cil space used calculation
> xfs: track CIL ticket reservation in percpu structure
> xfs: convert CIL busy extents to per-cpu
> xfs: Add order IDs to log items in CIL
> xfs: convert CIL to unordered per cpu lists
> xfs: convert log vector chain to use list heads
> xfs: move CIL ordering to the logvec chain
> xfs: avoid cil push lock if possible
> xfs: xlog_sync() manually adjusts grant head space
> xfs: expanding delayed logging design with background material
>
> Documentation/filesystems/xfs-delayed-logging-design.rst | 361 ++++++++++++++++++++++++++----
> fs/xfs/libxfs/xfs_log_format.h | 4 -
> fs/xfs/libxfs/xfs_types.h | 1 +
> fs/xfs/xfs_bio_io.c | 35 +++
> fs/xfs/xfs_buf.c | 2 +-
> fs/xfs/xfs_buf_item.c | 39 ++--
> fs/xfs/xfs_dquot_item.c | 2 +-
> fs/xfs/xfs_file.c | 20 +-
> fs/xfs/xfs_inode.c | 10 +-
> fs/xfs/xfs_inode_item.c | 18 +-
> fs/xfs/xfs_inode_item.h | 2 +-
> fs/xfs/xfs_linux.h | 2 +
> fs/xfs/xfs_log.c | 1015 +++++++++++++++++++++++++++++++++++++++---------------------------------------------
> fs/xfs/xfs_log.h | 66 ++----
> fs/xfs/xfs_log_cil.c | 822 ++++++++++++++++++++++++++++++++++++++++++++++++++------------------
> fs/xfs/xfs_log_priv.h | 114 +++++-----
> fs/xfs/xfs_super.c | 13 +-
> fs/xfs/xfs_super.h | 1 -
> fs/xfs/xfs_sysfs.c | 1 +
> fs/xfs/xfs_trace.c | 1 +
> fs/xfs/xfs_trans.c | 18 +-
> fs/xfs/xfs_trans.h | 5 +-
> fs/xfs/xfs_trans_ail.c | 11 +-
> fs/xfs/xfs_trans_priv.h | 3 +-
> include/linux/cpuhotplug.h | 1 +
> 25 files changed, 1603 insertions(+), 964 deletions(-)
>
> --
> Dave Chinner
> david@xxxxxxxxxxxxx
