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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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-Wflex-array-member-not-at-end was introduced in GCC-14, and we are
getting ready to enable it, globally.
Refactor a couple of structs that contain flexible arrays in the
middle by replacing them with unions.
So, with these changes, fix the following warnings:
fs/bcachefs/disk_accounting.c:429:51: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
fs/bcachefs/ec_types.h:8:41: warning: structure containing a flexible array member is not at the end of another structure [-Wflex-array-member-not-at-end]
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Prep work for the next patch, moving the lock_graph to btree_trans, and
off the stack.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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For bug diagnosis
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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- Don't call bch2_trans_relock() after dir_emit(); taking a transaction
restart here will cause us to emit the same dirent to userspace twice
- Fix incorrect checking of the return value on dir_emit(): "true" means
success, keep going, but bch2_dir_emit() needs to return true when
we're finished iterating.
https://github.com/koverstreet/bcachefs/issues/867
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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In 'bcachefs_metadata_extent_flags', we stopped requireding members_v1
to be present - only that either v1 or v2 is present.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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REQ_FUA means "skip the drive cache", and it can be used with reads to.
If there was a checksum error, we want to retry the whole read path, not
read it from cache again.
Suggested-by: Benjamin LaHaise <bcrl@kvack.org>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Add a sysfs attribute for checking whether read fua appears to behave
properly on a device.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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FUA is also allowed with reads, not just writes.
The specified behaviour is:
- If the location being read from in the drive cache is dirty, it's
flushed
- Read is serviced from media, not cache
It's documented in the NVME specification, and the nvme driver already
passes through REQ_FUA for reads, not just writes, so there's no reason
for the block layer to be disallowing it.
To validate behaviour, a simple test was run on a variety of hardware
that checks latency of repeated reads to the same location (cached
reads), random reads (uncached), and FUA reads to the same location.
Data:
- Samsung consumer SSDs
Reads appear to not be cached
- Seagate SCSI hard drives (ST20000NM002D)
Reads are cached, and FUA reads appear to work correctly
Link: https://lore.kernel.org/linux-block/20250311133517.3095878-1-kent.overstreet@linux.dev/
Link: https://lore.kernel.org/linux-bcachefs/26585.34711.506258.318405@quad.stoffel.home/T/#m5fffbc0e1c68cf0479c94b9f4ac1bef297333782
Cc: Jens Axboe <axboe@kernel.dk>
Cc: linux-block@vger.kernel.org
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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This adds shrinker.to_text() methods for our shrinkers and hooks them up
to our existing to_text() functions.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Previously, we added shrinker_to_text() and hooked it up to the OOM
report - now, the same report is available via debugfs.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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This patch:
- Changes show_mem() to always report on slab usage
- Instead of reporting on all slabs, we only report on top 10 slabs,
and in sorted order
- Also reports on shrinkers, with the new shrinkers_to_text().
Shrinkers need to be included in OOM/allocation failure reporting
because they're responsible for memory reclaim - if a shrinker isn't
giving up its memory, we need to know which one and why.
More OOM reporting can be moved to show_mem.c and improved, this patch
is only a start.
New example output on OOM/memory allocation failure:
00177 Mem-Info:
00177 active_anon:13706 inactive_anon:32266 isolated_anon:16
00177 active_file:1653 inactive_file:1822 isolated_file:0
00177 unevictable:0 dirty:0 writeback:0
00177 slab_reclaimable:6242 slab_unreclaimable:11168
00177 mapped:3824 shmem:3 pagetables:1266 bounce:0
00177 kernel_misc_reclaimable:0
00177 free:4362 free_pcp:35 free_cma:0
00177 Node 0 active_anon:54824kB inactive_anon:129064kB active_file:6612kB inactive_file:7288kB unevictable:0kB isolated(anon):64kB isolated(file):0kB mapped:15296kB dirty:0kB writeback:0kB shmem:12kB writeback_tmp:0kB kernel_stack:3392kB pagetables:5064kB all_unreclaimable? no
00177 DMA free:2232kB boost:0kB min:88kB low:108kB high:128kB reserved_highatomic:0KB active_anon:2924kB inactive_anon:6596kB active_file:428kB inactive_file:384kB unevictable:0kB writepending:0kB present:15992kB managed:15360kB mlocked:0kB bounce:0kB free_pcp:0kB local_pcp:0kB free_cma:0kB
00177 lowmem_reserve[]: 0 426 426 426
00177 DMA32 free:15092kB boost:5836kB min:8432kB low:9080kB high:9728kB reserved_highatomic:0KB active_anon:52196kB inactive_anon:122392kB active_file:6176kB inactive_file:7068kB unevictable:0kB writepending:0kB present:507760kB managed:441816kB mlocked:0kB bounce:0kB free_pcp:72kB local_pcp:0kB free_cma:0kB
00177 lowmem_reserve[]: 0 0 0 0
00177 DMA: 284*4kB (UM) 53*8kB (UM) 21*16kB (U) 11*32kB (U) 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 2248kB
00177 DMA32: 2765*4kB (UME) 375*8kB (UME) 57*16kB (UM) 5*32kB (U) 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 15132kB
00177 4656 total pagecache pages
00177 1031 pages in swap cache
00177 Swap cache stats: add 6572399, delete 6572173, find 488603/3286476
00177 Free swap = 509112kB
00177 Total swap = 2097148kB
00177 130938 pages RAM
00177 0 pages HighMem/MovableOnly
00177 16644 pages reserved
00177 Unreclaimable slab info:
00177 9p-fcall-cache total: 8.25 MiB active: 8.25 MiB
00177 kernfs_node_cache total: 2.15 MiB active: 2.15 MiB
00177 kmalloc-64 total: 2.08 MiB active: 2.07 MiB
00177 task_struct total: 1.95 MiB active: 1.95 MiB
00177 kmalloc-4k total: 1.50 MiB active: 1.50 MiB
00177 signal_cache total: 1.34 MiB active: 1.34 MiB
00177 kmalloc-2k total: 1.16 MiB active: 1.16 MiB
00177 bch_inode_info total: 1.02 MiB active: 922 KiB
00177 perf_event total: 1.02 MiB active: 1.02 MiB
00177 biovec-max total: 992 KiB active: 960 KiB
00177 Shrinkers:
00177 super_cache_scan: objects: 127
00177 super_cache_scan: objects: 106
00177 jbd2_journal_shrink_scan: objects: 32
00177 ext4_es_scan: objects: 32
00177 bch2_btree_cache_scan: objects: 8
00177 nr nodes: 24
00177 nr dirty: 0
00177 cannibalize lock: 0000000000000000
00177
00177 super_cache_scan: objects: 8
00177 super_cache_scan: objects: 1
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: linux-mm@kvack.org
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Add a few new shrinker stats.
number of objects requested to free, number of objects freed:
Shrinkers won't necessarily free all objects requested for a variety of
reasons, but if the two counts are wildly different something is likely
amiss.
.scan_objects runtime:
If one shrinker is taking an excessive amount of time to free
objects that will block kswapd from running other shrinkers.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: linux-mm@kvack.org
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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This adds a new callback method to shrinkers which they can use to
describe anything relevant to memory reclaim about their internal state,
for example object dirtyness.
This patch also adds shrinkers_to_text(), which reports on the top 10
shrinkers - by object count - in sorted order, to be used in OOM
reporting.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: linux-mm@kvack.org
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
From david@fromorbit.com Tue Aug 27 23:32:26 2024
> > + if (!mutex_trylock(&shrinker_mutex)) {
> > + seq_buf_puts(out, "(couldn't take shrinker lock)");
> > + return;
> > + }
>
> Please don't use the shrinker_mutex like this. There can be tens of
> thousands of entries in the shrinker list (because memcgs) and
> holding the shrinker_mutex for long running traversals like this is
> known to cause latency problems for memcg reaping. If we are at
> ENOMEM, the last thing we want to be doing is preventing memcgs from
> being reaped.
>
> > + list_for_each_entry(shrinker, &shrinker_list, list) {
> > + struct shrink_control sc = { .gfp_mask = GFP_KERNEL, };
>
> This iteration and counting setup is neither node or memcg aware.
> For node aware shrinkers, this will only count the items freeable
> on node 0, and ignore all the other memory in the system. For memcg
> systems, it will also only scan the root memcg and so miss counting
> any memory in memcg owned caches.
>
> IOWs, the shrinker iteration mechanism needs to iterate both by NUMA
> node and by memcg. On large machines with multiple nodes and hosting
> thousands of memcgs, a total shrinker state iteration is has to walk
> a -lot- of structures.
>
> And example of this is drop_slab() - called from
> /proc/sys/vm/drop_caches(). It does this to iterate all the
> shrinkers for all the nodes and memcgs in the system:
>
> static unsigned long drop_slab_node(int nid)
> {
> unsigned long freed = 0;
> struct mem_cgroup *memcg = NULL;
>
> memcg = mem_cgroup_iter(NULL, NULL, NULL);
> do {
> freed += shrink_slab(GFP_KERNEL, nid, memcg, 0);
> } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
>
> return freed;
> }
>
> void drop_slab(void)
> {
> int nid;
> int shift = 0;
> unsigned long freed;
>
> do {
> freed = 0;
> for_each_online_node(nid) {
> if (fatal_signal_pending(current))
> return;
>
> freed += drop_slab_node(nid);
> }
> } while ((freed >> shift++) > 1);
> }
>
> Hence any iteration for finding the 10 largest shrinkable caches in
> the system needs to do something similar. Only, it needs to iterate
> memcgs first and then aggregate object counts across all nodes for
> shrinkers that are NUMA aware.
>
> Because it needs direct access to the shrinkers, it will need to use
> the RCU lock + refcount method of traversal because that's the only
> safe way to go from memcg to shrinker instance. IOWs, it
> needs to mirror the code in shrink_slab/shrink_slab_memcg to obtain
> a safe reference to the relevant shrinker so it can call
> ->count_objects() and store a refcounted pointer to the shrinker(s)
> that will get printed out after the scan is done....
>
> Once the shrinker iteration is sorted out, I'll look further at the
> rest of the code in this patch...
>
> -Dave.
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This adds a seq_buf wrapper for string_get_size().
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Allow btree_insert_entry.ip_allocated to be passed in, so we get better
info on where alloc updates are coming from.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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If we detect an error that requires running a recovery pass, and we're
not in recovery, we won't be able to fix it until the next mount - make
sure we're noting in the superblock that it needs to run.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Like we just did with the data read path, emit a single error message
per btree node reads, nicely formatted, with all the actions we took
grouped together.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Part of the ongoing project to improve error messages by building them
up in printbufs and emitting them all at once, so that we can easily see
what events are related in the log.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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No longer has users, so we can kill it and rename
bch2_run_explicit_recovery_pass_persistent_locked().
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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The btree node read path calls this before returning the read error.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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We have a consolidated places for "this btree lost data, run this
repair", so use it.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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The btree node read path already logs btree node read errors, this isn't
needed.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Instead of emitting a message immediately when we get an error in the
read path, and then another at the end if we successfully retry - emit
one single log message before returning from bch2_rbio_retry().
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Pretty printer for bch_io_failures, to be used for better read error
messages.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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If the final line in in the message to be printed is blang, don't print
it.
This happens with indented printbufs - after a newline we emit spaces up
to the indent level.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Add async objs list for
- promote_op
- bch_read_bio
- btree_read_bio
- btree_write_bio
This gets us introspection on in-flight async ops, and because under the
hood it uses fast_lists (percpu slot buffer on top of a radix tree),
it'll be fast enough to enable in production.
This will be very helpful for debugging "something got stuck" issues,
which have been cropping up from time to time (in the CI, especially
with folio writeback).
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Debugging infrastructure for async objs: this lets us easily create
fast_lists for various object types so they'll be visible in debugfs.
Add new object types to the BCH_ASYNC_OBJS_TYPES() enum, and drop a
pretty-printer wrapper in async_objs.c.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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A fast "list" data structure, which is actually a radix tree, with an
IDA for slot allocation and a percpu buffer on top of that.
Items cannot be added or moved to the head or tail, only added at some
(arbitrary) position and removed. The advantage is that adding, removing
and iteration is generally lockless, only hitting the lock in ida when
the percpu buffer is full or empty.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Pretty printer for struct bch_read_bio.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Pretty printer for struct bio, to be used for async object debugging.
This is pretty minimal, we'll add more to it as we discover what we
need.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Convert device IO refs to enumerated_refs, for easier debugging of
refcount issues.
Simple conversion: enumerate all users and convert to the new helpers.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Drop the single-purpose write ref code in bcachefs.h, and convert to
enumarated refs.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Factor out the debug code for rw filesystem refs into a small library.
In release mode an enumerated ref is a normal percpu refcount, but in
debug mode all enumerated users of the ref get their own atomic_long_t
ref - making it much easier to chase down refcount usage bugs for when a
refcount has many users.
For debugging, we have enumerated_ref_to_text(), which prints the
current value of each different user.
Additionally, in debug mode enumerated_ref_stop() has a 10 second
timeout, after which it will dump outstanding refcounts.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Add a pass for checking the rebalance_work btree.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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Signed-off-by: Alan Huang <mmpgouride@gmail.com>
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
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