tjh.dev
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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Pull ext4 fixes from Ted Ts'o:
"Various bug fixes for ext4 fast commit and inline data handling.
Also fix regression introduced as part of moving to the new mount API"
* tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4:
fs/ext4: fix comments mentioning i_mutex
ext4: fix incorrect type issue during replay_del_range
jbd2: fix kernel-doc descriptions for jbd2_journal_shrink_{scan,count}()
ext4: fix potential NULL pointer dereference in ext4_fill_super()
jbd2: refactor wait logic for transaction updates into a common function
jbd2: cleanup unused functions declarations from jbd2.h
ext4: fix error handling in ext4_fc_record_modified_inode()
ext4: remove redundant max inline_size check in ext4_da_write_inline_data_begin()
ext4: fix error handling in ext4_restore_inline_data()
ext4: fast commit may miss file actions
ext4: fast commit may not fallback for ineligible commit
ext4: modify the logic of ext4_mb_new_blocks_simple
ext4: prevent used blocks from being allocated during fast commit replay
Pull perf tools fixes from Arnaldo Carvalho de Melo:
- Fix display of grouped aliased events in 'perf stat'.
- Add missing branch_sample_type to perf_event_attr__fprintf().
- Apply correct label to user/kernel symbols in branch mode.
- Fix 'perf ftrace' system_wide tracing, it has to be set before
creating the maps.
- Return error if procfs isn't mounted for PID namespaces when
synthesizing records for pre-existing processes.
- Set error stream of objdump process for 'perf annotate' TUI, to avoid
garbling the screen.
- Add missing arm64 support to perf_mmap__read_self(), the kernel part
got into 5.17.
- Check for NULL pointer before dereference writing debug info about a
sample.
- Update UAPI copies for asound, perf_event, prctl and kvm headers.
- Fix a typo in bpf_counter_cgroup.c.
* tag 'perf-tools-fixes-for-v5.17-2022-02-06' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux:
perf ftrace: system_wide collection is not effective by default
libperf: Add arm64 support to perf_mmap__read_self()
tools include UAPI: Sync sound/asound.h copy with the kernel sources
perf stat: Fix display of grouped aliased events
perf tools: Apply correct label to user/kernel symbols in branch mode
perf bpf: Fix a typo in bpf_counter_cgroup.c
perf synthetic-events: Return error if procfs isn't mounted for PID namespaces
perf session: Check for NULL pointer before dereference
perf annotate: Set error stream of objdump process for TUI
perf tools: Add missing branch_sample_type to perf_event_attr__fprintf()
tools headers UAPI: Sync linux/kvm.h with the kernel sources
tools headers UAPI: Sync linux/prctl.h with the kernel sources
perf beauty: Make the prctl arg regexp more strict to cope with PR_SET_VMA
tools headers cpufeatures: Sync with the kernel sources
tools headers UAPI: Sync linux/perf_event.h with the kernel sources
tools include UAPI: Sync sound/asound.h copy with the kernel sources
inode->i_mutex has been replaced with inode->i_rwsem long ago. Fix
comments still mentioning i_mutex.
Signed-off-by: hongnanli <hongnan.li@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220121070611.21618-1-hongnan.li@linux.alibaba.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Pull perf fixes from Borislav Petkov:
- Intel/PT: filters could crash the kernel
- Intel: default disable the PMU for SMM, some new-ish EFI firmware has
started using CPL3 and the PMU CPL filters don't discriminate against
SMM, meaning that CPL3 (userspace only) events now also count EFI/SMM
cycles.
- Fixup for perf_event_attr::sig_data
* tag 'perf_urgent_for_v5.17_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf/x86/intel/pt: Fix crash with stop filters in single-range mode
perf: uapi: Document perf_event_attr::sig_data truncation on 32 bit architectures
selftests/perf_events: Test modification of perf_event_attr::sig_data
perf: Copy perf_event_attr::sig_data on modification
x86/perf: Default set FREEZE_ON_SMI for all
The ftrace.target.system_wide must be set before invoking
evlist__create_maps(), otherwise it has no effect.
Fixes: 53be50282269b46c ("perf ftrace: Add 'latency' subcommand")
Signed-off-by: Changbin Du <changbin.du@gmail.com>
Acked-by: Namhyung Kim <namhyung@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20220127132010.4836-1-changbin.du@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
should not use fast commit log data directly, add le32_to_cpu().
Reported-by: kernel test robot <lkp@intel.com>
Fixes: 0b5b5a62b945 ("ext4: use ext4_ext_remove_space() for fast commit replay delete range")
Cc: stable@kernel.org
Signed-off-by: Xin Yin <yinxin.x@bytedance.com>
Reviewed-by: Ritesh Harjani <riteshh@linux.ibm.com>
Link: https://lore.kernel.org/r/20220126063146.2302-1-yinxin.x@bytedance.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Pull objtool fix from Borislav Petkov:
"Fix a potential truncated string warning triggered by gcc12"
* tag 'objtool_urgent_for_v5.17_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
objtool: Fix truncated string warning
Add a check for !buf->single before calling pt_buffer_region_size in a
place where a missing check can cause a kernel crash.
Fixes a bug introduced by commit 670638477aed ("perf/x86/intel/pt:
Opportunistically use single range output mode"), which added a
support for PT single-range output mode. Since that commit if a PT
stop filter range is hit while tracing, the kernel will crash because
of a null pointer dereference in pt_handle_status due to calling
pt_buffer_region_size without a ToPA configured.
The commit which introduced single-range mode guarded almost all uses of
the ToPA buffer variables with checks of the buf->single variable, but
missed the case where tracing was stopped by the PT hardware, which
happens when execution hits a configured stop filter.
Tested that hitting a stop filter while PT recording successfully
records a trace with this patch but crashes without this patch.
Fixes: 670638477aed ("perf/x86/intel/pt: Opportunistically use single range output mode")
Signed-off-by: Tristan Hume <tristan@thume.ca>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: stable@kernel.org
Link: https://lkml.kernel.org/r/20220127220806.73664-1-tristan@thume.ca
Add the arm64 variants for read_perf_counter() and read_timestamp().
Unfortunately the counter number is encoded into the instruction, so the
code is a bit verbose to enumerate all possible counters.
Tested-by: Masayoshi Mizuma <m.mizuma@jp.fujitsu.com>
Signed-off-by: Rob Herring <robh@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Tested-by: John Garry <john.garry@huawei.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: https://lore.kernel.org/r/20220201214056.702854-1-robh@kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-perf-users@vger.kernel.org
Add the description of @shrink and @sc in jbd2_journal_shrink_scan() and
jbd2_journal_shrink_count() kernel-doc comment to remove warnings found
by running scripts/kernel-doc, which is caused by using 'make W=1'.
fs/jbd2/journal.c:1296: warning: Function parameter or member 'shrink'
not described in 'jbd2_journal_shrink_scan'
fs/jbd2/journal.c:1296: warning: Function parameter or member 'sc' not
described in 'jbd2_journal_shrink_scan'
fs/jbd2/journal.c:1320: warning: Function parameter or member 'shrink'
not described in 'jbd2_journal_shrink_count'
fs/jbd2/journal.c:1320: warning: Function parameter or member 'sc' not
described in 'jbd2_journal_shrink_count'
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220110132841.34531-1-yang.lee@linux.alibaba.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Pull irq fix from Borislav Petkov:
"Remove a bogus warning introduced by the recent PCI MSI irq affinity
overhaul"
* tag 'irq_urgent_for_v5.17_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
PCI/MSI: Remove bogus warning in pci_irq_get_affinity()
On GCC 12, the build fails due to a possible truncated string:
check.c: In function 'validate_call':
check.c:2865:58: error: '%d' directive output may be truncated writing between 1 and 10 bytes into a region of size 9 [-Werror=format-truncation=]
2865 | snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);
| ^~
In theory it's a valid bug:
static char pvname[16];
int idx;
...
idx = (rel->addend / sizeof(void *));
snprintf(pvname, sizeof(pvname), "pv_ops[%d]", idx);
There are only 7 chars for %d while it could take up to 9, so the
printed "pv_ops[%d]" string could get truncated.
In reality the bug should never happen, because pv_ops only has ~80
entries, so 7 chars for the integer is more than enough. Still, it's
worth fixing. Bump the buffer size by 2 bytes to silence the warning.
[ jpoimboe: changed size to 19; massaged changelog ]
Fixes: db2b0c5d7b6f ("objtool: Support pv_opsindirect calls for noinstr")
Reported-by: Adam Borowski <kilobyte@angband.pl>
Reported-by: Martin Liška <mliska@suse.cz>
Signed-off-by: Sergei Trofimovich <slyich@gmail.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20220120233748.2062559-1-slyich@gmail.com
Due to the alignment requirements of siginfo_t, as described in
3ddb3fd8cdb0 ("signal, perf: Fix siginfo_t by avoiding u64 on 32-bit
architectures"), siginfo_t::si_perf_data is limited to an unsigned long.
However, perf_event_attr::sig_data is an u64, to avoid having to deal
with compat conversions. Due to being an u64, it may not immediately be
clear to users that sig_data is truncated on 32 bit architectures.
Add a comment to explicitly point this out, and hopefully help some
users save time by not having to deduce themselves what's happening.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Marco Elver <elver@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
Link: https://lore.kernel.org/r/20220131103407.1971678-3-elver@google.com
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