Since the size class is an artifact of an arbitrary anti fragmentation
strategy, it doesn't really make sense to persist it. Furthermore, most
of the size class logic assumes fresh block groups. That is of course
not a reasonable assumption -- we will be upgrading kernels with
existing filesystems whose block groups are not classified.

To work around those issues, implement logic to compute the size class
of the block groups as we cache them in. To perfectly assess the state
of a block group, we would have to read the entire extent tree (since
the free space cache mashes together contiguous extent items) which
would be prohibitively expensive for larger file systems with more
extents.

We can do it relatively cheaply by implementing a simple heuristic of
sampling a handful of extents and picking the smallest one we see. In
the happy case where the block group was classified, we will only see
extents of the correct size. In the unhappy case, we will hopefully find
one of the smaller extents, but there is no perfect answer anyway.
Autorelocation will eventually churn up the block group if there is
significant freeing anyway.

There was no regression in mount performance at end state of the fsperf
test suite, and the delay until the block group is marked cached is
minimized by the constant number of extent samples.
Signed-off-by: NBoris Burkov <boris@bur.io>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The aim of this patch is to reduce the fragmentation of block groups
under certain unhappy workloads. It is particularly effective when the
size of extents correlates with their lifetime, which is something we
have observed causing fragmentation in the fleet at Meta.

This patch categorizes extents into size classes:

- x < 128KiB: "small"
- 128KiB < x < 8MiB: "medium"
- x > 8MiB: "large"

and as much as possible reduces allocations of extents into block groups
that don't match the size class. This takes advantage of any (possible)
correlation between size and lifetime and also leaves behind predictable
re-usable gaps when extents are freed; small writes don't gum up bigger
holes.

Size classes are implemented in the following way:

- Mark each new block group with a size class of the first allocation
  that goes into it.

- Add two new passes to ffe: "unset size class" and "wrong size class".
  First, try only matching block groups, then try unset ones, then allow
  allocation of new ones, and finally allow mismatched block groups.

- Filtering is done just by skipping inappropriate ones, there is no
  special size class indexing.

Other solutions I considered were:

- A best fit allocator with an rb-tree. This worked well, as small
  writes didn't leak big holes from large freed extents, but led to
  regressions in ffe and write performance due to lock contention on
  the rb-tree with every allocation possibly updating it in parallel.
  Perhaps something clever could be done to do the updates in the
  background while being "right enough".

- A fixed size "working set". This prevents freeing an extent
  drastically changing where writes currently land, and seems like a
  good option too. Doesn't take advantage of size in any way.

- The same size class idea, but implemented with xarray marks. This
  turned out to be slower than looping the linked list and skipping
  wrong block groups, and is also less flexible since we must have only
  3 size classes (max #marks). With the current approach we can have as
  many as we like.

Performance testing was done via: https://github.com/josefbacik/fsperf
Of particular relevance are the new fragmentation specific tests.

A brief summary of the testing results:

- Neutral results on existing tests. There are some minor regressions
  and improvements here and there, but nothing that truly stands out as
  notable.
- Improvement on new tests where size class and extent lifetime are
  correlated. Fragmentation in these cases is completely eliminated
  and write performance is generally a little better. There is also
  significant improvement where extent sizes are just a bit larger than
  the size class boundaries.
- Regression on one new tests: where the allocations are sized
  intentionally a hair under the borders of the size classes. Results
  are neutral on the test that intentionally attacks this new scheme by
  mixing extent size and lifetime.

The full dump of the performance results can be found here:
https://bur.io/fsperf/size-class-2022-11-15.txt
(there are ANSI escape codes, so best to curl and view in terminal)

Here is a snippet from the full results for a new test which mixes
buffered writes appending to a long lived set of files and large short
lived fallocates:

bufferedappendvsfallocate results
         metric             baseline       current        stdev            diff
======================================================================================
avg_commit_ms                    31.13         29.20          2.67     -6.22%
bg_count                            14         15.60             0     11.43%
commits                          11.10         12.20          0.32      9.91%
elapsed                          27.30         26.40          2.98     -3.30%
end_state_mount_ns         11122551.90   10635118.90     851143.04     -4.38%
end_state_umount_ns           1.36e+09      1.35e+09   12248056.65     -1.07%
find_free_extent_calls       116244.30     114354.30        964.56     -1.63%
find_free_extent_ns_max      599507.20    1047168.20     103337.08     74.67%
find_free_extent_ns_mean       3607.19       3672.11        101.20      1.80%
find_free_extent_ns_min            500           512          6.67      2.40%
find_free_extent_ns_p50           2848          2876         37.65      0.98%
find_free_extent_ns_p95           4916          5000         75.45      1.71%
find_free_extent_ns_p99       20734.49      20920.48       1670.93      0.90%
frag_pct_max                     61.67             0          8.05   -100.00%
frag_pct_mean                    43.59             0          6.10   -100.00%
frag_pct_min                     25.91             0         16.60   -100.00%
frag_pct_p50                     42.53             0          7.25   -100.00%
frag_pct_p95                     61.67             0          8.05   -100.00%
frag_pct_p99                     61.67             0          8.05   -100.00%
fragmented_bg_count               6.10             0          1.45   -100.00%
max_commit_ms                    49.80            46          5.37     -7.63%
sys_cpu                           2.59          2.62          0.29      1.39%
write_bw_bytes                1.62e+08      1.68e+08   17975843.50      3.23%
write_clat_ns_mean            57426.39      54475.95       2292.72     -5.14%
write_clat_ns_p50             46950.40      42905.60       2101.35     -8.62%
write_clat_ns_p99            148070.40     143769.60       2115.17     -2.90%
write_io_kbytes                4194304       4194304             0      0.00%
write_iops                     2476.15       2556.10        274.29      3.23%
write_lat_ns_max            2101667.60    2251129.50     370556.59      7.11%
write_lat_ns_mean             59374.91      55682.00       2523.09     -6.22%
write_lat_ns_min              17353.10         16250       1646.08     -6.36%

There are some mixed improvements/regressions in most metrics along with
an elimination of fragmentation in this workload.

On the balance, the drastic 1->0 improvement in the happy cases seems
worth the mix of regressions and improvements we do observe.

Some considerations for future work:

- Experimenting with more size classes
- More hinting/search ordering work to approximate a best-fit allocator
Signed-off-by: NBoris Burkov <boris@bur.io>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

find_free_extent is a complicated function. It consists (at least) of:

- a hint that jumps into the middle of a for loop macro
- a middle loop trying every raid level
- an outer loop ascending through ffe loop levels
- complicated logic for skipping some of those ffe loop levels
- multiple underlying in-bg allocators (zoned, cluster, no cluster)

Which is all to say that more tracing is helpful for debugging its
behavior. Add two new tracepoints: at the entrance to the block_groups
loop (hit for every raid level and every ffe_ctl loop) and at the point
we seriously consider a block_group for allocation. This way we can see
the whole path through the algorithm, including hints, multiple loops,
etc.
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: NBoris Burkov <boris@bur.io>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The allocator tracepoints currently have a pile of values from ffe_ctl.
In modifying the allocator and adding more tracepoints, I found myself
adding to the already long argument list of the tracepoints. It makes it
a lot simpler to just send in the ffe_ctl itself.
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NAnand Jain <anand.jain@oracle.com>
Signed-off-by: NBoris Burkov <boris@bur.io>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Given that wait is always set to 1, so remove the argument.
Last use of wait with 0 was in 0c304304 ("Btrfs: remove
csum_bytes_left").
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

We currently use 'ret' and 'err' to track the return value for
log_dir_items(), which is confusing and likely the cause for previous
bugs where log_dir_items() did not return an error when it should, fixed
in previous patches.

So change this and use only a single variable, 'ret', to track the return
value. This is simpler and makes it similar to most of the existing code.
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Currently we use the value 1 for BTRFS_LOG_FORCE_COMMIT, but that value
has a few inconveniences:

1) If it's ever used by btrfs_log_inode(), or any function down the call
   chain, we have to remember to btrfs_set_log_full_commit(), which is
   repetitive and has a chance to be forgotten in future use cases.
   btrfs_log_inode_parent() only calls btrfs_set_log_full_commit() when
   it gets a negative value from btrfs_log_inode();

2) Down the call chain of btrfs_log_inode(), we may have functions that
   need to force a log commit, but can return either an error (negative
   value), false (0) or true (1). So they are forced to return some
   random negative to force a log commit - using BTRFS_LOG_FORCE_COMMIT
   would make the intention more clear. Currently the only example is
   flush_dir_items_batch().

So turn BTRFS_LOG_FORCE_COMMIT into a negative value. The chosen value
is -(MAX_ERRNO + 1), so that it does not overlap any errno value and makes
it easier to debug.
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NFilipe Manana <fdmanana@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

The header file linux/mm.h provides PAGE_ALIGN, PAGE_ALIGNED,
PAGE_ALIGN_DOWN macros. Use these macros to make code more
concise.
Signed-off-by: NYushan Zhou <katrinzhou@tencent.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

When btrfs_get_chunk_map fails to allocate a new em the cleanup does not
need to be done so the goto target is out_err, which is consistent with
current coding style.
Signed-off-by: NPeng Hao <flyingpeng@tencent.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
[ update changelog ]
Signed-off-by: NDavid Sterba <dsterba@suse.com>

We had a recent bug that would have been caught by a newer compiler with
-Wmaybe-uninitialized and would have saved us a month of failing tests
that I didn't have time to investigate.
Reviewed-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

With -Wmaybe-uninitialized compiler complains about ret being possibly
uninitialized, which isn't possible as the WQ_ constants are set only
from our code, however we can handle the default case and get rid of the
warning.

The value is set to BLK_STS_IOERR so it does not issue any IO and could
be potentially detected, but this is basically a "cannot happen" error.
To catch any problems during development use the assert.
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
[ set the error in default: ]
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Fix an uninitialized warning we get with -Wmaybe-uninitialized where it
thought zno may have been uninitialized, in both cases it depends on
zinfo->zone_cache but we know the value won't change between checks.
Reported-by: NJosef Bacik <josef@toxicpanda.com>
Link: https://lore.kernel.org/linux-btrfs/af6c527cbd8bdc782e50bd33996ee83acc3a16fb.1671221596.git.josef@toxicpanda.com/Signed-off-by: NNaohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

We only have 3 possible mirrors, and we have ASSERT()'s to make sure
we're not passing in an invalid super mirror into this function, so
technically this value isn't uninitialized.  However
-Wmaybe-uninitialized will complain, so set it to U64_MAX so if we don't
have ASSERT()'s turned on it'll error out later on when it see's the
zone is beyond our maximum zones.
Reviewed-by: NNaohiro Aota <naohiro.aota@wdc.com>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

We will pass in the parent and p pointer into our tree_search function
to avoid doing a second search when inserting a new extent state into
the tree.  However because this is conditional upon passing in these
pointers the compiler seems to think these values can be uninitialized
if we're using -Wmaybe-uninitialized.  Fix this by initializing these
values.
Reviewed-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

reclaim isn't set in the alloc case, however we only care about
reclaim in the !alloc case.  This isn't an actual problem, however
-Wmaybe-uninitialized will complain, so initialize reclaim to quiet the
compiler.
Reviewed-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Anybody that calls get_inode_gen() can have an uninitialized gen if
there's an error.  This isn't a big deal because all the users just exit
if they get an error, however it makes -Wmaybe-uninitialized complain,
so fix this up to always initialize the passed in gen, this quiets all
of the uninitialized warnings in send.c.
Reviewed-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NQu Wenruo <wqu@suse.com>
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

We can conditionally pass in a locked page, and then we'll use that page
range to skip marking errors as that will happen in another layer.
However this causes the compiler to complain because it doesn't
understand we only use these values when we have the page.  Make the
compiler stop complaining by setting these values to 0.
Reviewed-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

While trying to sync messages.[ch] I ended up with this dependency on
messages.h in the rest of btrfs-progs code base because it's where
btrfs_abort_transaction() was now held.  We want to keep messages.[ch]
limited to the kernel code, and the btrfs_abort_transaction() code
better fits in the transaction code and not in messages.
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: NJosef Bacik <josef@toxicpanda.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
[ move the __cold attributes ]
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Now that none of the functions called by btrfs_merge_delayed_refs() needs
a btrfs_trans_handle, directly pass in a btrfs_fs_info to
btrfs_merge_delayed_refs().
Reviewed-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Now that drop_delayed_ref() doesn't need a btrfs_trans_handle, drop it
from insert_delayed_ref() as well.
Reviewed-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Now that drop_delayed_ref() doesn't get the btrfs_trans_handle passed in
anymore, we can get rid of it in merge_ref() as well.
Reviewed-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

drop_delayed_ref() doesn't use the btrfs_trans_handle it gets passed in,
so remove it.
Reviewed-by: NQu Wenruo <wqu@suse.com>
Reviewed-by: NJosef Bacik <josef@toxicpanda.com>
Signed-off-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

Both Rich Felker and Yoshinori Sato haven't done any work on arch/sh
for a while. As I have been maintaining Debian's sh4 port since 2014,
I am interested to keep the architecture alive.
Signed-off-by: NJohn Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Acked-by: NYoshinori Sato <ysato@users.sourceforge.jp>
Acked-by: NGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Pull tracing fix from Steven Rostedt:
 "Fix showing of TASK_COMM_LEN instead of its value

  The TASK_COMM_LEN was converted from a macro into an enum so that BTF
  would have access to it. But this unfortunately caused TASK_COMM_LEN
  to display in the format fields of trace events, as they are created
  by the TRACE_EVENT() macro and such, macros convert to their values,
  where as enums do not.

  To handle this, instead of using the field itself to be display, save
  the value of the array size as another field in the trace_event_fields
  structure, and use that instead.

  Not only does this fix the issue, but also converts the other trace
  events that have this same problem (but were not breaking tooling).

  With this change, the original work around b3bc8547 ("tracing:
  Have TRACE_DEFINE_ENUM affect trace event types as well") could be
  reverted (but that should be done in the merge window)"

* tag 'trace-v6.2-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing: Fix TASK_COMM_LEN in trace event format file

Pull btrfs fixes from David Sterba:

 - one more fix for a tree-log 'write time corruption' report, update
   the last dir index directly and don't keep in the log context

 - do VFS-level inode lock around FIEMAP to prevent a deadlock with
   concurrent fsync, the extent-level lock is not sufficient

 - don't cache a single-device filesystem device to avoid cases when a
   loop device is reformatted and the entry gets stale

* tag 'for-6.2-rc7-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: free device in btrfs_close_devices for a single device filesystem
  btrfs: lock the inode in shared mode before starting fiemap
  btrfs: simplify update of last_dir_index_offset when logging a directory

Pull USB fixes from Greg KH:
 "Here are 2 small USB driver fixes that resolve some reported
  regressions and one new device quirk. Specifically these are:

   - new quirk for Alcor Link AK9563 smartcard reader

   - revert of u_ether gadget change in 6.2-rc1 that caused problems

   - typec pin probe fix

  All of these have been in linux-next with no reported problems"

* tag 'usb-6.2-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb:
  usb: core: add quirk for Alcor Link AK9563 smartcard reader
  usb: typec: altmodes/displayport: Fix probe pin assign check
  Revert "usb: gadget: u_ether: Do not make UDC parent of the net device"

Pull EFI fix from Ard Biesheuvel:
 "A fix from Darren to widen the SMBIOS match for detecting Ampere Altra
  machines with problematic firmware. In the mean time, we are working
  on a more precise check, but this is still work in progress"

* tag 'efi-fixes-for-v6.2-4' of git://git.kernel.org/pub/scm/linux/kernel/git/efi/efi:
  arm64: efi: Force the use of SetVirtualAddressMap() on eMAG and Altra Max machines

Pull powerpc fixes from Michael Ellerman:

 - Fix interrupt exit race with security mitigation switching.

 - Don't select ARCH_WANTS_NO_INSTR until warnings are fixed.

 - Build fix for CONFIG_NUMA=n.

Thanks to Nicholas Piggin, Randy Dunlap, and Sachin Sant.

* tag 'powerpc-6.2-5' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux:
  powerpc/64s/interrupt: Fix interrupt exit race with security mitigation switch
  powerpc/kexec_file: fix implicit decl error
  powerpc: Don't select ARCH_WANTS_NO_INSTR

When we upgraded our kernel, we started seeing some page corruption like
the following consistently:

  BUG: Bad page state in process ganesha.nfsd  pfn:1304ca
  page:0000000022261c55 refcount:0 mapcount:-128 mapping:0000000000000000 index:0x0 pfn:0x1304ca
  flags: 0x17ffffc0000000()
  raw: 0017ffffc0000000 ffff8a513ffd4c98 ffffeee24b35ec08 0000000000000000
  raw: 0000000000000000 0000000000000001 00000000ffffff7f 0000000000000000
  page dumped because: nonzero mapcount
  CPU: 0 PID: 15567 Comm: ganesha.nfsd Kdump: loaded Tainted: P    B      O      5.10.158-1.nutanix.20221209.el7.x86_64 #1
  Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 04/05/2016
  Call Trace:
   dump_stack+0x74/0x96
   bad_page.cold+0x63/0x94
   check_new_page_bad+0x6d/0x80
   rmqueue+0x46e/0x970
   get_page_from_freelist+0xcb/0x3f0
   ? _cond_resched+0x19/0x40
   __alloc_pages_nodemask+0x164/0x300
   alloc_pages_current+0x87/0xf0
   skb_page_frag_refill+0x84/0x110
   ...

Sometimes, it would also show up as corruption in the free list pointer
and cause crashes.

After bisecting the issue, we found the issue started from commit
e320d301 ("mm/page_alloc.c: fix freeing non-compound pages"):

	if (put_page_testzero(page))
		free_the_page(page, order);
	else if (!PageHead(page))
		while (order-- > 0)
			free_the_page(page + (1 << order), order);

So the problem is the check PageHead is racy because at this point we
already dropped our reference to the page.  So even if we came in with
compound page, the page can already be freed and PageHead can return
false and we will end up freeing all the tail pages causing double free.

Fixes: e320d301 ("mm/page_alloc.c: fix freeing non-compound pages")
Link: https://lore.kernel.org/lkml/BYAPR02MB448855960A9656EEA81141FC94D99@BYAPR02MB4488.namprd02.prod.outlook.com/
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@vger.kernel.org
Signed-off-by: NChunwei Chen <david.chen@nutanix.com>
Reviewed-by: NVlastimil Babka <vbabka@suse.cz>
Reviewed-by: NMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

After commit 3087c61e ("tools/testing/selftests/bpf: replace open-coded 16 with TASK_COMM_LEN"),
the content of the format file under
/sys/kernel/tracing/events/task/task_newtask was changed from
  field:char comm[16];    offset:12;    size:16;    signed:0;
to
  field:char comm[TASK_COMM_LEN];    offset:12;    size:16;    signed:0;

John reported that this change breaks older versions of perfetto.
Then Mathieu pointed out that this behavioral change was caused by the
use of __stringify(_len), which happens to work on macros, but not on enum
labels. And he also gave the suggestion on how to fix it:
  :One possible solution to make this more robust would be to extend
  :struct trace_event_fields with one more field that indicates the length
  :of an array as an actual integer, without storing it in its stringified
  :form in the type, and do the formatting in f_show where it belongs.

The result as follows after this change,
$ cat /sys/kernel/tracing/events/task/task_newtask/format
        field:char comm[16];    offset:12;      size:16;        signed:0;

Link: https://lore.kernel.org/lkml/Y+QaZtz55LIirsUO@google.com/
Link: https://lore.kernel.org/linux-trace-kernel/20230210155921.4610-1-laoar.shao@gmail.com/
Link: https://lore.kernel.org/linux-trace-kernel/20230212151303.12353-1-laoar.shao@gmail.com

Cc: stable@vger.kernel.org
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Kajetan Puchalski <kajetan.puchalski@arm.com>
CC: Qais Yousef <qyousef@layalina.io>
Fixes: 3087c61e ("tools/testing/selftests/bpf: replace open-coded 16 with TASK_COMM_LEN")
Reported-by: NJohn Stultz <jstultz@google.com>
Debugged-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Suggested-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
Suggested-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NYafang Shao <laoar.shao@gmail.com>
Signed-off-by: NSteven Rostedt (Google) <rostedt@goodmis.org>

Pull spi fixes from Mark Brown:
 "A couple of hopefully final fixes for spi: one driver specific fix for
  an issue with very large transfers and a fix for an issue with the
  locking fixes in spidev merged earlier this release cycle which was
  missed"

* tag 'spi-fix-v6.2-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi:
  spi: spidev: fix a recursive locking error
  spi: dw: Fix wrong FIFO level setting for long xfers

Pull x86 fixes from Ingo Molnar:
 "Fix a kprobes bug, plus add a new Intel model number to the upstream
  <asm/intel-family.h> header for drivers to use"

* tag 'x86-urgent-2023-02-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/cpu: Add Lunar Lake M
  x86/kprobes: Fix 1 byte conditional jump target

Pull locking fix from Ingo Molnar:
 "Fix an rtmutex missed-wakeup bug"

* tag 'locking-urgent-2023-02-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  rtmutex: Ensure that the top waiter is always woken up

Pull cxl fixes from Dan Williams:
 "Two fixups for CXL (Compute Express Link) in presence of passthrough
  decoders.

  This primarily helps developers using the QEMU CXL emulation, but with
  the impending arrival of CXL switches these types of topologies will
  be of interest to end users.

   - Fix a crash when shutting down regions in the presence of
     passthrough decoders

   - Fix region creation to understand passthrough decoders instead of
     the narrower definition of passthrough ports"

* tag 'cxl-fixes-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl:
  cxl/region: Fix passthrough-decoder detection
  cxl/region: Fix null pointer dereference for resetting decoder

Pull libnvdimm fixes from Dan Williams:
 "A fix for an issue that could causes users to inadvertantly reserve
  too much capacity when debugging the KMSAN and persistent memory
  namespace, a lockdep fix, and a kernel-doc build warning:

   - Resolve the conflict between KMSAN and NVDIMM with respect to
     reserving pmem namespace / volume capacity for larger sizeof(struct
     page)

   - Fix a lockdep warning in the the NFIT code

   - Fix a kernel-doc build warning"

* tag 'libnvdimm-fixes-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/nvdimm/nvdimm:
  nvdimm: Support sizeof(struct page) > MAX_STRUCT_PAGE_SIZE
  ACPI: NFIT: fix a potential deadlock during NFIT teardown
  dax: super.c: fix kernel-doc bad line warning

Pull memblock revert from Mike Rapoport:
 "Revert 'mm: Always release pages to the buddy allocator in
  memblock_free_late()'

  The pages being freed by memblock_free_late() have already been
  initialized, but if they are in the deferred init range,
  __free_one_page() might access nearby uninitialized pages when trying
  to coalesce buddies, which will cause a crash.

  A proper fix will be more involved so revert this change for the time
  being"

* tag 'fixes-2023-02-11' of git://git.kernel.org/pub/scm/linux/kernel/git/rppt/memblock:
  Revert "mm: Always release pages to the buddy allocator in memblock_free_late()."

Pull clk fixes from Stephen Boyd:
 "Two clk driver fixes

   - Use devm_kasprintf() to avoid overflows when forming clk names in
     the Microchip PolarFire driver

   - Fix the pretty broken Ingenic JZ4760 M/N/OD calculation to actually
     work and find proper divisors"

* tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux:
  clk: ingenic: jz4760: Update M/N/OD calculation algorithm
  clk: microchip: mpfs-ccc: Use devm_kasprintf() for allocating formatted strings

Pull pin control fixes from Linus Walleij:
 "Some assorted pin control fixes, the most interesting will be the
  Intel patch fixing a classic problem: laptop touchpad IRQs...

   - Some pin drive register fixes in the Mediatek driver.

   - Return proper error code in the Aspeed driver, and revert and
     ill-advised force-disablement patch that needs to be reworked.

   - Fix AMD driver debug output.

   - Fix potential NULL dereference in the Single driver.

   - Fix a group definition error in the Qualcomm SM8450 LPASS driver.

   - Restore pins used in direct IRQ mode in the Intel driver (This
     fixes some laptop touchpads!)"

* tag 'pinctrl-v6.2-3' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl:
  pinctrl: intel: Restore the pins that used to be in Direct IRQ mode
  pinctrl: qcom: sm8450-lpass-lpi: correct swr_rx_data group
  pinctrl: aspeed: Revert "Force to disable the function's signal"
  pinctrl: single: fix potential NULL dereference
  pinctrl: amd: Fix debug output for debounce time
  pinctrl: aspeed: Fix confusing types in return value
  pinctrl: mediatek: Fix the drive register definition of some Pins

Pull PCI fixes from Bjorn Helgaas:

 - Move to a shared PCI git tree (Bjorn Helgaas)

 - Add Krzysztof Wilczyński as another PCI maintainer (Lorenzo
   Pieralisi)

 - Revert a couple ASPM patches to fix suspend/resume regressions (Bjorn
   Helgaas)

* tag 'pci-v6.2-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/pci/pci:
  Revert "PCI/ASPM: Refactor L1 PM Substates Control Register programming"
  Revert "PCI/ASPM: Save L1 PM Substates Capability for suspend/resume"
  MAINTAINERS: Promote Krzysztof to PCI controller maintainer
  MAINTAINERS: Move to shared PCI tree