- 30 Jan, 2024 9 commits
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Leo Yan authored
In the Linux perf tool, the ring buffer serves not only as a medium for transferring PMU event data but also as a vital mechanism for hardware tracing using technologies like Intel PT and Arm CoreSight, etc. Consequently, the ring buffer mechanism plays a crucial role by ensuring high throughput for data transfer between the kernel and user space while avoiding excessive overhead caused by the ring buffer itself. This commit documents the ring buffer mechanism in detail. It explains the implementation of both the regular ring buffer and the AUX ring buffer. Additionally, it covers how these ring buffers support various tracing modes and explains the synchronization with memory barriers. Signed-off-by:
Leo Yan <leo.yan@linaro.org> Reviewed-by:
James Clark <james.clark@arm.com> Reviewed-by:
Namhyung Kim <namhyung@kernel.org> Signed-off-by:
Jonathan Corbet <corbet@lwn.net> Link: https://lore.kernel.org/r/20240102085001.228815-1-leo.yan@linaro.org
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Jonathan Corbet authored
Add some subsection headings and reorder entries so that the page makes a bit more sense. With luck, adding some ordering will also reduce merge conflicts due to everybody adding new entries at the end. Signed-off-by:
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Jonathan Corbet authored
Add subsections in an attempt to bring a bit order to this page; also sort most subsections into alphabetical order. With luck all this will help to prevent merge conflicts on this page due to everybody adding entries at the end. Signed-off-by:
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Federico Vaga authored
To begin with: - locking/index.rst - locking/lockdep-design.rst - locking/lockstat.rst - locking/lockturture.rst - locking/locktypes.rst And RCU/torture.rst to avoid broken references. Signed-off-by:Federico Vaga <federico.vaga@vaga.pv.it> Signed-off-by:
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Randy Dunlap authored
Since 2014 kernel-doc has supported describing object-like macros but it is not documented anywhere. I should have required some documentation for it when I merged the patch. :( There are currently only 3 uses of this (all in DRM headers, in include/drm/*.h). Add object-like macro kernel-doc documentation now so that more may know about it and use it. Fixes: cbb4d3e6 ("scripts/kernel-doc: handle object-like macros") Signed-off-by:
Randy Dunlap <rdunlap@infradead.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: linux-doc@vger.kernel.org Acked-by:
Daniel Vetter <daniel.vetter@ffwll.ch> Signed-off-by:
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Randy Dunlap authored
Linux kernel does not use "MACDOC" in any documenation or any source files, so stop searching for it. Signed-off-by:
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Vegard Nossum authored
It's good to be clear about who the intended target audience for any given piece of documentation is, as this will help us put new text in the correct place. Let's encourage submitters to state it explicitly rather than relying on where they placed it in the directory hierarchy as there isn't necessarily a one-to-one correspondence between them. Target audience: documentation contributors and reviewers. Signed-off-by:
Vegard Nossum <vegard.nossum@oracle.com> Acked-by:
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Anna-Maria Behnsen authored
To prevent this, do the pre-processing only for lines which are no comments, e.g. do not start with ' *'. Suggested-by:
Matthew Wilcox <willy@infradead.org> Signed-off-by:
Anna-Maria Behnsen <anna-maria@linutronix.de> Tested-by:
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Anna-Maria Behnsen authored
Reformat lines in kernel-doc comments, which make use of the backslash at the end to suggest it is a multi-line comment. kernel-doc is able to process e.g. the short description of a function properly, even if it is across two lines. No functional change. Signed-off-by:
Jani Nikula <jani.nikula@intel.com> Acked-by:
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- 23 Jan, 2024 4 commits
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Lukas Bulwahn authored
Commit 1db9d06aaa55 ("mm/slab: remove CONFIG_SLAB from all Kconfig and Makefile") removes the config SLAB and makes the SLUB allocator the only default allocator in the kernel. Hence, the advice on reducing OS jitter due to kworker kernel threads to build with CONFIG_SLUB instead of CONFIG_SLAB is obsolete. Remove the obsolete advice to build with SLUB instead of SLAB. Signed-off-by:Lukas Bulwahn <lukas.bulwahn@gmail.com> Acked-by:
Vlastimil Babka <vbabka@suse.cz> Signed-off-by:
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Vegard Nossum authored
This comment about DRM drivers has been there since the first git commit. It simply doesn't belong in kernel-parameters; remove it. Signed-off-by:
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Hu Haowen authored
Since the mailing archive list lkml.org is obsolete, change the links into lore.kernel.org's ones. Signed-off-by:
Hu Haowen <2023002089@link.tyut.edu.cn> Signed-off-by:
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Gustavo Sousa authored
When on the documentation home page, there won't be any ".current" element since no entry from the TOC was selected yet. That results in a javascript error. Fix that by only trying to set the scrollTop if we have matches for current entries. Signed-off-by:
Gustavo Sousa <gustavo.sousa@intel.com> Signed-off-by:
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- 21 Jan, 2024 27 commits
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Linus Torvalds authored
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https://evilpiepirate.org/git/bcachefsLinus Torvalds authored
Pull more bcachefs updates from Kent Overstreet: "Some fixes, Some refactoring, some minor features: - Assorted prep work for disk space accounting rewrite - BTREE_TRIGGER_ATOMIC: after combining our trigger callbacks, this makes our trigger context more explicit - A few fixes to avoid excessive transaction restarts on multithreaded workloads: fstests (in addition to ktest tests) are now checking slowpath counters, and that's shaking out a few bugs - Assorted tracepoint improvements - Starting to break up bcachefs_format.h and move on disk types so they're with the code they belong to; this will make room to start documenting the on disk format better. - A few minor fixes" * tag 'bcachefs-2024-01-21' of https://evilpiepirate.org/git/bcachefs: (46 commits) bcachefs: Improve inode_to_text() bcachefs: logged_ops_format.h bcachefs: reflink_format.h bcachefs; extents_format.h bcachefs: ec_format.h bcachefs: subvolume_format.h bcachefs: snapshot_format.h bcachefs: alloc_background_format.h bcachefs: xattr_format.h bcachefs: dirent_format.h bcachefs: inode_format.h bcachefs; quota_format.h bcachefs: sb-counters_format.h bcachefs: counters.c -> sb-counters.c bcachefs: comment bch_subvolume bcachefs: bch_snapshot::btime bcachefs: add missing __GFP_NOWARN bcachefs: opts->compression can now also be applied in the background bcachefs: Prep work for variable size btree node buffers bcachefs: grab s_umount only if snapshotting ... -
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull timer updates from Thomas Gleixner: "Updates for time and clocksources: - A fix for the idle and iowait time accounting vs CPU hotplug. The time is reset on CPU hotplug which makes the accumulated systemwide time jump backwards. - Assorted fixes and improvements for clocksource/event drivers" * tag 'timers-core-2024-01-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: tick-sched: Fix idle and iowait sleeptime accounting vs CPU hotplug clocksource/drivers/ep93xx: Fix error handling during probe clocksource/drivers/cadence-ttc: Fix some kernel-doc warnings clocksource/drivers/timer-ti-dm: Fix make W=n kerneldoc warnings clocksource/timer-riscv: Add riscv_clock_shutdown callback dt-bindings: timer: Add StarFive JH8100 clint dt-bindings: timer: thead,c900-aclint-mtimer: separate mtime and mtimecmp regs -
git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linuxLinus Torvalds authored
Pull powerpc fixes from Aneesh Kumar: - Increase default stack size to 32KB for Book3S Thanks to Michael Ellerman. * tag 'powerpc-6.8-2' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: powerpc/64s: Increase default stack size to 32KB
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Kent Overstreet authored
Add line breaks - inode_to_text() is now much easier to read. Signed-off-by:Kent Overstreet <kent.overstreet@linux.dev>
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Kent Overstreet authored
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Kent Overstreet authored
Signed-off-by: -
Kent Overstreet authored
Signed-off-by: -
Kent Overstreet authored
Signed-off-by: -
Kent Overstreet authored
Signed-off-by: -
Kent Overstreet authored
Signed-off-by: -
Kent Overstreet authored
Signed-off-by: -
Kent Overstreet authored
Signed-off-by: -
Kent Overstreet authored
Signed-off-by: -
Kent Overstreet authored
Signed-off-by: -
Kent Overstreet authored
Signed-off-by: -
Kent Overstreet authored
bcachefs_format.h has gotten too big; let's do some organizing. Signed-off-by: -
Kent Overstreet authored
Signed-off-by: -
Kent Overstreet authored
Signed-off-by: -
Kent Overstreet authored
Add a field to bch_snapshot for creation time; this will be important when we start exposing the snapshot tree to userspace. Signed-off-by: -
Kent Overstreet authored
Signed-off-by: -
Kent Overstreet authored
The "apply this compression method in the background" paths now use the compression option if background_compression is not set; this means that setting or changing the compression option will cause existing data to be compressed accordingly in the background. Signed-off-by: -
Kent Overstreet authored
bcachefs btree nodes are big - typically 256k - and btree roots are pinned in memory. As we're now up to 18 btrees, we now have significant memory overhead in mostly empty btree roots. And in the future we're going to start enforcing that certain btree node boundaries exist, to solve lock contention issues - analagous to XFS's AGIs. Thus, we need to start allocating smaller btree node buffers when we can. This patch changes code that refers to the filesystem constant c->opts.btree_node_size to refer to the btree node buffer size - btree_buf_bytes() - where appropriate. Signed-off-by: -
Su Yue authored
When I was testing mongodb over bcachefs with compression, there is a lockdep warning when snapshotting mongodb data volume. $ cat test.sh prog=bcachefs $prog subvolume create /mnt/data $prog subvolume create /mnt/data/snapshots while true;do $prog subvolume snapshot /mnt/data /mnt/data/snapshots/$(date +%s) sleep 1s done $ cat /etc/mongodb.conf systemLog: destination: file logAppend: true path: /mnt/data/mongod.log storage: dbPath: /mnt/data/ lockdep reports: [ 3437.452330] ====================================================== [ 3437.452750] WARNING: possible circular locking dependency detected [ 3437.453168] 6.7.0-rc7-custom+ #85 Tainted: G E [ 3437.453562] ------------------------------------------------------ [ 3437.453981] bcachefs/35533 is trying to acquire lock: [ 3437.454325] ffffa0a02b2b1418 (sb_writers#10){.+.+}-{0:0}, at: filename_create+0x62/0x190 [ 3437.454875] but task is already holding lock: [ 3437.455268] ffffa0a02b2b10e0 (&type->s_umount_key#48){.+.+}-{3:3}, at: bch2_fs_file_ioctl+0x232/0xc90 [bcachefs] [ 3437.456009] which lock already depends on the new lock. [ 3437.456553] the existing dependency chain (in reverse order) is: [ 3437.457054] -> #3 (&type->s_umount_key#48){.+.+}-{3:3}: [ 3437.457507] down_read+0x3e/0x170 [ 3437.457772] bch2_fs_file_ioctl+0x232/0xc90 [bcachefs] [ 3437.458206] __x64_sys_ioctl+0x93/0xd0 [ 3437.458498] do_syscall_64+0x42/0xf0 [ 3437.458779] entry_SYSCALL_64_after_hwframe+0x6e/0x76 [ 3437.459155] -> #2 (&c->snapshot_create_lock){++++}-{3:3}: [ 3437.459615] down_read+0x3e/0x170 [ 3437.459878] bch2_truncate+0x82/0x110 [bcachefs] [ 3437.460276] bchfs_truncate+0x254/0x3c0 [bcachefs] [ 3437.460686] notify_change+0x1f1/0x4a0 [ 3437.461283] do_truncate+0x7f/0xd0 [ 3437.461555] path_openat+0xa57/0xce0 [ 3437.461836] do_filp_open+0xb4/0x160 [ 3437.462116] do_sys_openat2+0x91/0xc0 [ 3437.462402] __x64_sys_openat+0x53/0xa0 [ 3437.462701] do_syscall_64+0x42/0xf0 [ 3437.462982] entry_SYSCALL_64_after_hwframe+0x6e/0x76 [ 3437.463359] -> #1 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}: [ 3437.463843] down_write+0x3b/0xc0 [ 3437.464223] bch2_write_iter+0x5b/0xcc0 [bcachefs] [ 3437.464493] vfs_write+0x21b/0x4c0 [ 3437.464653] ksys_write+0x69/0xf0 [ 3437.464839] do_syscall_64+0x42/0xf0 [ 3437.465009] entry_SYSCALL_64_after_hwframe+0x6e/0x76 [ 3437.465231] -> #0 (sb_writers#10){.+.+}-{0:0}: [ 3437.465471] __lock_acquire+0x1455/0x21b0 [ 3437.465656] lock_acquire+0xc6/0x2b0 [ 3437.465822] mnt_want_write+0x46/0x1a0 [ 3437.465996] filename_create+0x62/0x190 [ 3437.466175] user_path_create+0x2d/0x50 [ 3437.466352] bch2_fs_file_ioctl+0x2ec/0xc90 [bcachefs] [ 3437.466617] __x64_sys_ioctl+0x93/0xd0 [ 3437.466791] do_syscall_64+0x42/0xf0 [ 3437.466957] entry_SYSCALL_64_after_hwframe+0x6e/0x76 [ 3437.467180] other info that might help us debug this: [ 3437.469670] 2 locks held by bcachefs/35533: other info that might help us debug this: [ 3437.467507] Chain exists of: sb_writers#10 --> &c->snapshot_create_lock --> &type->s_umount_key#48 [ 3437.467979] Possible unsafe locking scenario: [ 3437.468223] CPU0 CPU1 [ 3437.468405] ---- ---- [ 3437.468585] rlock(&type->s_umount_key#48); [ 3437.468758] lock(&c->snapshot_create_lock); [ 3437.469030] lock(&type->s_umount_key#48); [ 3437.469291] rlock(sb_writers#10); [ 3437.469434] *** DEADLOCK *** [ 3437.469670] 2 locks held by bcachefs/35533: [ 3437.469838] #0: ffffa0a02ce00a88 (&c->snapshot_create_lock){++++}-{3:3}, at: bch2_fs_file_ioctl+0x1e3/0xc90 [bcachefs] [ 3437.470294] #1: ffffa0a02b2b10e0 (&type->s_umount_key#48){.+.+}-{3:3}, at: bch2_fs_file_ioctl+0x232/0xc90 [bcachefs] [ 3437.470744] stack backtrace: [ 3437.470922] CPU: 7 PID: 35533 Comm: bcachefs Kdump: loaded Tainted: G E 6.7.0-rc7-custom+ #85 [ 3437.471313] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.16.3-1-1 04/01/2014 [ 3437.471694] Call Trace: [ 3437.471795] <TASK> [ 3437.471884] dump_stack_lvl+0x57/0x90 [ 3437.472035] check_noncircular+0x132/0x150 [ 3437.472202] __lock_acquire+0x1455/0x21b0 [ 3437.472369] lock_acquire+0xc6/0x2b0 [ 3437.472518] ? filename_create+0x62/0x190 [ 3437.472683] ? lock_is_held_type+0x97/0x110 [ 3437.472856] mnt_want_write+0x46/0x1a0 [ 3437.473025] ? filename_create+0x62/0x190 [ 3437.473204] filename_create+0x62/0x190 [ 3437.473380] user_path_create+0x2d/0x50 [ 3437.473555] bch2_fs_file_ioctl+0x2ec/0xc90 [bcachefs] [ 3437.473819] ? lock_acquire+0xc6/0x2b0 [ 3437.474002] ? __fget_files+0x2a/0x190 [ 3437.474195] ? __fget_files+0xbc/0x190 [ 3437.474380] ? lock_release+0xc5/0x270 [ 3437.474567] ? __x64_sys_ioctl+0x93/0xd0 [ 3437.474764] ? __pfx_bch2_fs_file_ioctl+0x10/0x10 [bcachefs] [ 3437.475090] __x64_sys_ioctl+0x93/0xd0 [ 3437.475277] do_syscall_64+0x42/0xf0 [ 3437.475454] entry_SYSCALL_64_after_hwframe+0x6e/0x76 [ 3437.475691] RIP: 0033:0x7f2743c313af ====================================================== In __bch2_ioctl_subvolume_create(), we grab s_umount unconditionally and unlock it at the end of the function. There is a comment "why do we need this lock?" about the lock coming from commit 42d23732 ("bcachefs: Snapshot creation, deletion") The reason is that __bch2_ioctl_subvolume_create() calls sync_inodes_sb() which enforce locked s_umount to writeback all dirty nodes before doing snapshot works. Fix it by read locking s_umount for snapshotting only and unlocking s_umount after sync_inodes_sb(). Signed-off-by:Su Yue <glass.su@suse.com> Signed-off-by:
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Su Yue authored
bch_fs::snapshots is allocated by kvzalloc in __snapshot_t_mut. It should be freed by kvfree not kfree. Or umount will triger: [ 406.829178 ] BUG: unable to handle page fault for address: ffffe7b487148008 [ 406.830676 ] #PF: supervisor read access in kernel mode [ 406.831643 ] #PF: error_code(0x0000) - not-present page [ 406.832487 ] PGD 0 P4D 0 [ 406.832898 ] Oops: 0000 [#1] PREEMPT SMP PTI [ 406.833512 ] CPU: 2 PID: 1754 Comm: umount Kdump: loaded Tainted: G OE 6.7.0-rc7-custom+ #90 [ 406.834746 ] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux 1.16.3-1-1 04/01/2014 [ 406.835796 ] RIP: 0010:kfree+0x62/0x140 [ 406.836197 ] Code: 80 48 01 d8 0f 82 e9 00 00 00 48 c7 c2 00 00 00 80 48 2b 15 78 9f 1f 01 48 01 d0 48 c1 e8 0c 48 c1 e0 06 48 03 05 56 9f 1f 01 <48> 8b 50 08 48 89 c7 f6 c2 01 0f 85 b0 00 00 00 66 90 48 8b 07 f6 [ 406.837810 ] RSP: 0018:ffffb9d641607e48 EFLAGS: 00010286 [ 406.838213 ] RAX: ffffe7b487148000 RBX: ffffb9d645200000 RCX: ffffb9d641607dc4 [ 406.838738 ] RDX: 000065bb00000000 RSI: ffffffffc0d88b84 RDI: ffffb9d645200000 [ 406.839217 ] RBP: ffff9a4625d00068 R08: 0000000000000001 R09: 0000000000000001 [ 406.839650 ] R10: 0000000000000001 R11: 000000000000001f R12: ffff9a4625d4da80 [ 406.840055 ] R13: ffff9a4625d00000 R14: ffffffffc0e2eb20 R15: 0000000000000000 [ 406.840451 ] FS: 00007f0a264ffb80(0000) GS:ffff9a4e2d500000(0000) knlGS:0000000000000000 [ 406.840851 ] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 406.841125 ] CR2: ffffe7b487148008 CR3: 000000018c4d2000 CR4: 00000000000006f0 [ 406.841464 ] Call Trace: [ 406.841583 ] <TASK> [ 406.841682 ] ? __die+0x1f/0x70 [ 406.841828 ] ? page_fault_oops+0x159/0x470 [ 406.842014 ] ? fixup_exception+0x22/0x310 [ 406.842198 ] ? exc_page_fault+0x1ed/0x200 [ 406.842382 ] ? asm_exc_page_fault+0x22/0x30 [ 406.842574 ] ? bch2_fs_release+0x54/0x280 [bcachefs] [ 406.842842 ] ? kfree+0x62/0x140 [ 406.842988 ] ? kfree+0x104/0x140 [ 406.843138 ] bch2_fs_release+0x54/0x280 [bcachefs] [ 406.843390 ] kobject_put+0xb7/0x170 [ 406.843552 ] deactivate_locked_super+0x2f/0xa0 [ 406.843756 ] cleanup_mnt+0xba/0x150 [ 406.843917 ] task_work_run+0x59/0xa0 [ 406.844083 ] exit_to_user_mode_prepare+0x197/0x1a0 [ 406.844302 ] syscall_exit_to_user_mode+0x16/0x40 [ 406.844510 ] do_syscall_64+0x4e/0xf0 [ 406.844675 ] entry_SYSCALL_64_after_hwframe+0x6e/0x76 [ 406.844907 ] RIP: 0033:0x7f0a2664e4fb Signed-off-by:
Brian Foster <bfoster@redhat.com> Signed-off-by:
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Kent Overstreet authored
Fixes: 023f9ac9 bcachefs: Delete dio read alignment check Reported-by:
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Colin Ian King authored
The variable tmp is being assigned a value but it isn't being read afterwards. The assignment is redundant and so tmp can be removed. Cleans up clang scan build warning: warning: Although the value stored to 'ret' is used in the enclosing expression, the value is never actually read from 'ret' [deadcode.DeadStores] Signed-off-by:
Colin Ian King <colin.i.king@gmail.com> Reviewed-by:
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