Michal Koutný <mkoutny@suse.com> wrote:
> It was reported that v5.14 behaves differently when enforcing
> RLIMIT_NPROC limit, namely, it allows one more task than previously.
> This is consequence of the commit 21d1c5e386 ("Reimplement
> RLIMIT_NPROC on top of ucounts") that missed the sharpness of
> equality in the forking path.
This can be fixed either by fixing the test or by moving the increment
to be before the test. Fix it my moving copy_creds which contains
the increment before is_ucounts_overlimit.
In the case of CLONE_NEWUSER the ucounts in the task_cred changes.
The function is_ucounts_overlimit needs to use the final version of
the ucounts for the new process. Which means moving the
is_ucounts_overlimit test after copy_creds is necessary.
Both the test in fork and the test in set_user were semantically
changed when the code moved to ucounts. The change of the test in
fork was bad because it was before the increment. The test in
set_user was wrong and the change to ucounts fixed it. So this
fix only restores the old behavior in one lcation not two.
Link: https://lkml.kernel.org/r/20220204181144.24462-1-mkoutny@suse.com
Link: https://lkml.kernel.org/r/20220216155832.680775-2-ebiederm@xmission.com
Cc: stable@vger.kernel.org
Reported-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Fixes: 21d1c5e386 ("Reimplement RLIMIT_NPROC on top of ucounts")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Solar Designer <solar@openwall.com> wrote:
> I'm not aware of anyone actually running into this issue and reporting
> it. The systems that I personally know use suexec along with rlimits
> still run older/distro kernels, so would not yet be affected.
>
> So my mention was based on my understanding of how suexec works, and
> code review. Specifically, Apache httpd has the setting RLimitNPROC,
> which makes it set RLIMIT_NPROC:
>
> https://httpd.apache.org/docs/2.4/mod/core.html#rlimitnproc
>
> The above documentation for it includes:
>
> "This applies to processes forked from Apache httpd children servicing
> requests, not the Apache httpd children themselves. This includes CGI
> scripts and SSI exec commands, but not any processes forked from the
> Apache httpd parent, such as piped logs."
>
> In code, there are:
>
> ./modules/generators/mod_cgid.c: ( (cgid_req.limits.limit_nproc_set) && ((rc = apr_procattr_limit_set(procattr, APR_LIMIT_NPROC,
> ./modules/generators/mod_cgi.c: ((rc = apr_procattr_limit_set(procattr, APR_LIMIT_NPROC,
> ./modules/filters/mod_ext_filter.c: rv = apr_procattr_limit_set(procattr, APR_LIMIT_NPROC, conf->limit_nproc);
>
> For example, in mod_cgi.c this is in run_cgi_child().
>
> I think this means an httpd child sets RLIMIT_NPROC shortly before it
> execs suexec, which is a SUID root program. suexec then switches to the
> target user and execs the CGI script.
>
> Before 2863643fb8, the setuid() in suexec would set the flag, and the
> target user's process count would be checked against RLIMIT_NPROC on
> execve(). After 2863643fb8, the setuid() in suexec wouldn't set the
> flag because setuid() is (naturally) called when the process is still
> running as root (thus, has those limits bypass capabilities), and
> accordingly execve() would not check the target user's process count
> against RLIMIT_NPROC.
In commit 2863643fb8 ("set_user: add capability check when
rlimit(RLIMIT_NPROC) exceeds") capable calls were added to set_user to
make it more consistent with fork. Unfortunately because of call site
differences those capable calls were checking the credentials of the
user before set*id() instead of after set*id().
This breaks enforcement of RLIMIT_NPROC for applications that set the
rlimit and then call set*id() while holding a full set of
capabilities. The capabilities are only changed in the new credential
in security_task_fix_setuid().
The code in apache suexec appears to follow this pattern.
Commit 909cc4ae86f3 ("[PATCH] Fix two bugs with process limits
(RLIMIT_NPROC)") where this check was added describes the targes of this
capability check as:
2/ When a root-owned process (e.g. cgiwrap) sets up process limits and then
calls setuid, the setuid should fail if the user would then be running
more than rlim_cur[RLIMIT_NPROC] processes, but it doesn't. This patch
adds an appropriate test. With this patch, and per-user process limit
imposed in cgiwrap really works.
So the original use case of this check also appears to match the broken
pattern.
Restore the enforcement of RLIMIT_NPROC by removing the bad capable
checks added in set_user. This unfortunately restores the
inconsistent state the code has been in for the last 11 years, but
dealing with the inconsistencies looks like a larger problem.
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20210907213042.GA22626@openwall.com/
Link: https://lkml.kernel.org/r/20220212221412.GA29214@openwall.com
Link: https://lkml.kernel.org/r/20220216155832.680775-1-ebiederm@xmission.com
Fixes: 2863643fb8 ("set_user: add capability check when rlimit(RLIMIT_NPROC) exceeds")
History-Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Reviewed-by: Solar Designer <solar@openwall.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Sysfs support might be disabled so we need to guard the code that
instantiates "compression" attribute with an #ifdef.
Fixes: b1ae6dc41e ("module: add in-kernel support for decompressing")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
When commit e6ac2450d6 ("bpf: Support bpf program calling kernel function") added
kfunc support, it defined reg2btf_ids as a cheap way to translate the verifier
reg type to the appropriate btf_vmlinux BTF ID, however
commit c25b2ae136 ("bpf: Replace PTR_TO_XXX_OR_NULL with PTR_TO_XXX | PTR_MAYBE_NULL")
moved the __BPF_REG_TYPE_MAX from the last member of bpf_reg_type enum to after
the base register types, and defined other variants using type flag
composition. However, now, the direct usage of reg->type to index into
reg2btf_ids may no longer fall into __BPF_REG_TYPE_MAX range, and hence lead to
out of bounds access and kernel crash on dereference of bad pointer.
Fixes: c25b2ae136 ("bpf: Replace PTR_TO_XXX_OR_NULL with PTR_TO_XXX | PTR_MAYBE_NULL")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220216201943.624869-1-memxor@gmail.com
As 'swsusp_check' open 'hib_resume_bdev', if call 'create_basic_memory_bitmaps'
failed, we need to close 'hib_resume_bdev' in 'load_image_and_restore' function.
Signed-off-by: Ye Bin <yebin10@huawei.com>
[ rjw: Subject ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
BTFGen needs to run the core relocation logic in order to understand
what are the types involved in a given relocation.
Currently bpf_core_apply_relo() calculates and **applies** a relocation
to an instruction. Having both operations in the same function makes it
difficult to only calculate the relocation without patching the
instruction. This commit splits that logic in two different phases: (1)
calculate the relocation and (2) patch the instruction.
For the first phase bpf_core_apply_relo() is renamed to
bpf_core_calc_relo_insn() who is now only on charge of calculating the
relocation, the second phase uses the already existing
bpf_core_patch_insn(). bpf_object__relocate_core() uses both of them and
the BTFGen will use only bpf_core_calc_relo_insn().
Signed-off-by: Mauricio Vásquez <mauricio@kinvolk.io>
Signed-off-by: Rafael David Tinoco <rafael.tinoco@aquasec.com>
Signed-off-by: Lorenzo Fontana <lorenzo.fontana@elastic.co>
Signed-off-by: Leonardo Di Donato <leonardo.didonato@elastic.co>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220215225856.671072-2-mauricio@kinvolk.io
When dumping lock_classes information via /proc/lockdep, we can't take
the lockdep lock as the lock hold time is indeterminate. Iterating
over all_lock_classes without holding lock can be dangerous as there
is a slight chance that it may branch off to other lists leading to
infinite loop or even access invalid memory if changes are made to
all_lock_classes list in parallel.
To avoid this problem, iteration of lock classes is now done directly
on the lock_classes array itself. The lock_classes_in_use bitmap is
checked to see if the lock class is being used. To avoid iterating
the full array all the times, a new max_lock_class_idx value is added
to track the maximum lock_class index that is currently being used.
We can theoretically take the lockdep lock for iterating all_lock_classes
when other lockdep files (lockdep_stats and lock_stat) are accessed as
the lock hold time will be shorter for them. For consistency, they are
also modified to iterate the lock_classes array directly.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220211035526.1329503-2-longman@redhat.com
To prepare for supporting each feature of the housekeeping cpumask
toward cpuset, prepare each of the HK_FLAG_* entries to move to their
own cpumask with enforcing to fetch them individually. The new
constraint is that multiple HK_FLAG_* entries can't be mixed together
anymore in a single call to housekeeping cpumask().
This will later allow, for example, to runtime modify the cpulist passed
through "isolcpus=", "nohz_full=" and "rcu_nocbs=" kernel boot
parameters.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Phil Auld <pauld@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220207155910.527133-3-frederic@kernel.org
When a new threshold breaching stall happens after a psi event was
generated and within the window duration, the new event is not
generated because the events are rate-limited to one per window. If
after that no new stall is recorded then the event will not be
generated even after rate-limiting duration has passed. This is
happening because with no new stall, window_update will not be called
even though threshold was previously breached. To fix this, record
threshold breaching occurrence and generate the event once window
duration is passed.
Suggested-by: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Suren Baghdasaryan <surenb@google.com>
Link: https://lore.kernel.org/r/1643093818-19835-1-git-send-email-huangzhaoyang@gmail.com
In a typical memory tiering system, there's no CPU in slow (PMEM) NUMA
nodes. But if the number of the hint page faults on a PMEM node is
the max for a task, The current NUMA balancing policy may try to place
the task on the PMEM node instead of DRAM node. This is unreasonable,
because there's no CPU in PMEM NUMA nodes. To fix this, CPU-less
nodes are ignored when searching the migration target node for a task
in this patch.
To test the patch, we run a workload that accesses more memory in PMEM
node than memory in DRAM node. Without the patch, the PMEM node will
be chosen as preferred node in task_numa_placement(). While the DRAM
node will be chosen instead with the patch.
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220214121553.582248-2-ying.huang@intel.com
The NUMA topology parameters (sched_numa_topology_type,
sched_domains_numa_levels, and sched_max_numa_distance, etc.)
identified by scheduler may be wrong for systems with CPU-less nodes.
For example, the ACPI SLIT of a system with CPU-less persistent
memory (Intel Optane DCPMM) nodes is as follows,
[000h 0000 4] Signature : "SLIT" [System Locality Information Table]
[004h 0004 4] Table Length : 0000042C
[008h 0008 1] Revision : 01
[009h 0009 1] Checksum : 59
[00Ah 0010 6] Oem ID : "XXXX"
[010h 0016 8] Oem Table ID : "XXXXXXX"
[018h 0024 4] Oem Revision : 00000001
[01Ch 0028 4] Asl Compiler ID : "INTL"
[020h 0032 4] Asl Compiler Revision : 20091013
[024h 0036 8] Localities : 0000000000000004
[02Ch 0044 4] Locality 0 : 0A 15 11 1C
[030h 0048 4] Locality 1 : 15 0A 1C 11
[034h 0052 4] Locality 2 : 11 1C 0A 1C
[038h 0056 4] Locality 3 : 1C 11 1C 0A
While the `numactl -H` output is as follows,
available: 4 nodes (0-3)
node 0 cpus: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71
node 0 size: 64136 MB
node 0 free: 5981 MB
node 1 cpus: 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95
node 1 size: 64466 MB
node 1 free: 10415 MB
node 2 cpus:
node 2 size: 253952 MB
node 2 free: 253920 MB
node 3 cpus:
node 3 size: 253952 MB
node 3 free: 253951 MB
node distances:
node 0 1 2 3
0: 10 21 17 28
1: 21 10 28 17
2: 17 28 10 28
3: 28 17 28 10
In this system, there are only 2 sockets. In each memory controller,
both DRAM and PMEM DIMMs are installed. Although the physical NUMA
topology is simple, the logical NUMA topology becomes a little
complex. Because both the distance(0, 1) and distance (1, 3) are less
than the distance (0, 3), it appears that node 1 sits between node 0
and node 3. And the whole system appears to be a glueless mesh NUMA
topology type. But it's definitely not, there is even no CPU in node 3.
This isn't a practical problem now yet. Because the PMEM nodes (node
2 and node 3 in example system) are offlined by default during system
boot. So init_numa_topology_type() called during system boot will
ignore them and set sched_numa_topology_type to NUMA_DIRECT. And
init_numa_topology_type() is only called at runtime when a CPU of a
never-onlined-before node gets plugged in. And there's no CPU in the
PMEM nodes. But it appears better to fix this to make the code more
robust.
To test the potential problem. We have used a debug patch to call
init_numa_topology_type() when the PMEM node is onlined (in
__set_migration_target_nodes()). With that, the NUMA parameters
identified by scheduler is as follows,
sched_numa_topology_type: NUMA_GLUELESS_MESH
sched_domains_numa_levels: 4
sched_max_numa_distance: 28
To fix the issue, the CPU-less nodes are ignored when the NUMA topology
parameters are identified. Because a node may become CPU-less or not
at run time because of CPU hotplug, the NUMA topology parameters need
to be re-initialized at runtime for CPU hotplug too.
With the patch, the NUMA parameters identified for the example system
above is as follows,
sched_numa_topology_type: NUMA_DIRECT
sched_domains_numa_levels: 2
sched_max_numa_distance: 21
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220214121553.582248-1-ying.huang@intel.com
In some places, kernel/sched code calls cpumask_weight() to check if
any bit of a given cpumask is set. We can do it more efficiently with
cpumask_empty() because cpumask_empty() stops traversing the cpumask as
soon as it finds first set bit, while cpumask_weight() counts all bits
unconditionally.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20220210224933.379149-23-yury.norov@gmail.com
WRITE_KERN is supposed to overwrite some kernel text, namely
do_overwritten() function.
But at the time being it overwrites do_overwritten() function
descriptor, not function text.
Fix it by dereferencing the function descriptor to obtain
function text pointer. Export dereference_function_descriptor()
for when LKDTM is built as a module.
And make do_overwritten() noinline so that it is really
do_overwritten() which is called by lkdtm_WRITE_KERN().
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/31e58eaffb5bc51c07d8d4891d1982100ade8cfc.1644928018.git.christophe.leroy@csgroup.eu
Now kfunc call uses s32 to represent the offset between the address of
kfunc and __bpf_call_base, but it doesn't check whether or not s32 will
be overflowed. The overflow is possible when kfunc is in module and the
offset between module and kernel is greater than 2GB. Take arm64 as an
example, before commit b2eed9b588 ("arm64/kernel: kaslr: reduce module
randomization range to 2 GB"), the offset between module symbol and
__bpf_call_base will in 4GB range due to KASLR and may overflow s32.
So add an extra checking to reject these invalid kfunc calls.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220215065732.3179408-1-houtao1@huawei.com
The per-cpu @printk_pending variable can be updated from
sleepable contexts, such as:
get_random_bytes()
warn_unseeded_randomness()
printk_deferred()
defer_console_output()
and can be updated from interrupt contexts, such as:
handle_irq_event_percpu()
__irq_wake_thread()
wake_up_process()
try_to_wake_up()
select_task_rq()
select_fallback_rq()
printk_deferred()
defer_console_output()
and can be updated from NMI contexts, such as:
vprintk()
if (in_nmi()) defer_console_output()
Therefore the atomic variant of the updating functions must be used.
Replace __this_cpu_xchg() with this_cpu_xchg().
Replace __this_cpu_or() with this_cpu_or().
Reported-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/87iltld4ue.fsf@jogness.linutronix.de
PASIDs are process-wide. It was attempted to use refcounted PASIDs to
free them when the last thread drops the refcount. This turned out to
be complex and error prone. Given the fact that the PASID space is 20
bits, which allows up to 1M processes to have a PASID associated
concurrently, PASID resource exhaustion is not a realistic concern.
Therefore, it was decided to simplify the approach and stick with lazy
on demand PASID allocation, but drop the eager free approach and make an
allocated PASID's lifetime bound to the lifetime of the process.
Get rid of the refcounting mechanisms and replace/rename the interfaces
to reflect this new approach.
[ bp: Massage commit message. ]
Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Joerg Roedel <jroedel@suse.de>
Link: https://lore.kernel.org/r/20220207230254.3342514-6-fenghua.yu@intel.com
As previously discussed(https://lkml.org/lkml/2022/1/20/51),
cpuset_attach() is affected with similar cpu hotplug race,
as follow scenario:
cpuset_attach() cpu hotplug
--------------------------- ----------------------
down_write(cpuset_rwsem)
guarantee_online_cpus() // (load cpus_attach)
sched_cpu_deactivate
set_cpu_active()
// will change cpu_active_mask
set_cpus_allowed_ptr(cpus_attach)
__set_cpus_allowed_ptr_locked()
// (if the intersection of cpus_attach and
cpu_active_mask is empty, will return -EINVAL)
up_write(cpuset_rwsem)
To avoid races such as described above, protect cpuset_attach() call
with cpu_hotplug_lock.
Fixes: be367d0992 ("cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time")
Cc: stable@vger.kernel.org # v2.6.32+
Reported-by: Zhao Gongyi <zhaogongyi@huawei.com>
Signed-off-by: Zhang Qiao <zhangqiao22@huawei.com>
Acked-by: Waiman Long <longman@redhat.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
A new mm doesn't have a PASID yet when it's created. Initialize
the mm's PASID on fork() or for init_mm to INVALID_IOASID (-1).
INIT_PASID (0) is reserved for kernel legacy DMA PASID. It cannot be
allocated to a user process. Initializing the process's PASID to 0 may
cause confusion that's why the process uses the reserved kernel legacy
DMA PASID. Initializing the PASID to INVALID_IOASID (-1) explicitly
tells the process doesn't have a valid PASID yet.
Even though the only user of mm_pasid_init() is in fork.c, define it in
<linux/sched/mm.h> as the first of three mm/pasid life cycle functions
(init/set/drop) to keep these all together.
Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20220207230254.3342514-5-fenghua.yu@intel.com
In some places, RCU code calls cpumask_weight() to check if any bit of a
given cpumask is set. We can do it more efficiently with cpumask_empty()
because cpumask_empty() stops traversing the cpumask as soon as it finds
first set bit, while cpumask_weight() counts all bits unconditionally.
Signed-off-by: Yury Norov <yury.norov@gmail.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
This is a rarely used function, so uninlining its 3 instructions
is probably a win or a wash - but the main motivation is to
make <linux/rcuwait.h> independent of task_struct details.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
KCSAN reports data races between the rcu_segcblist_clear_flags() and
rcu_segcblist_set_flags() functions, though misreporting the latter
as a call to rcu_segcblist_is_enabled() from call_rcu(). This commit
converts the updates of this field to WRITE_ONCE(), relying on the
resulting unmarked reads to continue to detect buggy concurrent writes
to this field.
Reported-by: Zhouyi Zhou <zhouzhouyi@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>
Recording the work creation stack trace for KASAN reports in
call_rcu() is expensive, due to unwinding the stack, but also
due to acquiring depot_lock inside stackdepot (which may be contended).
Because calling kasan_record_aux_stack_noalloc() does not require
interrupts to already be disabled, this may unnecessarily extend
the time with interrupts disabled.
Therefore, move calling kasan_record_aux_stack() before the section
with interrupts disabled.
Acked-by: Marco Elver <elver@google.com>
Signed-off-by: Zqiang <qiang1.zhang@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Because __call_rcu() is invoked only by call_rcu(), this commit inlines
the former into the latter.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
As we handle parallel CPU bringup, we will need to take care to avoid
spawning multiple boost threads, or race conditions when setting their
affinity. Spotted by Paul McKenney.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
During panic(), if another CPU is writing heavily the kernel log (e.g.
via /dev/kmsg), then the panic CPU may livelock writing out its messages
to the console. Note when too many messages are dropped during panic and
suppress further printk, except from the panic CPU. This could result in
some important messages being dropped. However, messages are already
being dropped, so this approach at least prevents a livelock.
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220202171821.179394-4-stephen.s.brennan@oracle.com
A CPU executing with console lock spinning enabled might be halted
during a panic. Before the panicking CPU calls console_flush_on_panic(),
it may call console_trylock(), which attempts to optimistically spin,
deadlocking the panic CPU:
CPU 0 (panic CPU) CPU 1
----------------- ------
printk() {
vprintk_func() {
vprintk_default() {
vprintk_emit() {
console_unlock() {
console_lock_spinning_enable();
... printing to console ...
panic() {
crash_smp_send_stop() {
NMI -------------------> HALT
}
atomic_notifier_call_chain() {
printk() {
...
console_trylock_spinnning() {
// optimistic spin infinitely
This hang during panic can be induced when a kdump kernel is loaded, and
crash_kexec_post_notifiers=1 is present on the kernel command line. The
following script which concurrently writes to /dev/kmsg, and triggers a
panic, can result in this hang:
#!/bin/bash
date
# 991 chars (based on log buffer size):
chars="$(printf 'a%.0s' {1..991})"
while :; do
echo $chars > /dev/kmsg
done &
echo c > /proc/sysrq-trigger &
date
exit
To avoid this deadlock, ensure that console_trylock_spinning() does not
allow spinning once a panic has begun.
Fixes: dbdda842fe ("printk: Add console owner and waiter logic to load balance console writes")
Suggested-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Stephen Brennan <stephen.s.brennan@oracle.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220202171821.179394-3-stephen.s.brennan@oracle.com
The problem I'm addressing was discovered by the LTP test covering
cve-2018-1000204.
A short description of what happens follows:
1) The test case issues a command code 00 (TEST UNIT READY) via the SG_IO
interface with: dxfer_len == 524288, dxdfer_dir == SG_DXFER_FROM_DEV
and a corresponding dxferp. The peculiar thing about this is that TUR
is not reading from the device.
2) In sg_start_req() the invocation of blk_rq_map_user() effectively
bounces the user-space buffer. As if the device was to transfer into
it. Since commit a45b599ad8 ("scsi: sg: allocate with __GFP_ZERO in
sg_build_indirect()") we make sure this first bounce buffer is
allocated with GFP_ZERO.
3) For the rest of the story we keep ignoring that we have a TUR, so the
device won't touch the buffer we prepare as if the we had a
DMA_FROM_DEVICE type of situation. My setup uses a virtio-scsi device
and the buffer allocated by SG is mapped by the function
virtqueue_add_split() which uses DMA_FROM_DEVICE for the "in" sgs (here
scatter-gather and not scsi generics). This mapping involves bouncing
via the swiotlb (we need swiotlb to do virtio in protected guest like
s390 Secure Execution, or AMD SEV).
4) When the SCSI TUR is done, we first copy back the content of the second
(that is swiotlb) bounce buffer (which most likely contains some
previous IO data), to the first bounce buffer, which contains all
zeros. Then we copy back the content of the first bounce buffer to
the user-space buffer.
5) The test case detects that the buffer, which it zero-initialized,
ain't all zeros and fails.
One can argue that this is an swiotlb problem, because without swiotlb
we leak all zeros, and the swiotlb should be transparent in a sense that
it does not affect the outcome (if all other participants are well
behaved).
Copying the content of the original buffer into the swiotlb buffer is
the only way I can think of to make swiotlb transparent in such
scenarios. So let's do just that if in doubt, but allow the driver
to tell us that the whole mapped buffer is going to be overwritten,
in which case we can preserve the old behavior and avoid the performance
impact of the extra bounce.
Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Pull scheduler fix from Borislav Petkov:
"Fix a NULL-ptr dereference when recalculating a sched entity's weight"
* tag 'sched_urgent_for_v5.17_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/fair: Fix fault in reweight_entity
Pull perf fix from Borislav Petkov:
"Prevent cgroup event list corruption when switching events"
* tag 'perf_urgent_for_v5.17_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
perf: Fix list corruption in perf_cgroup_switch()
Pull seccomp fixes from Kees Cook:
"This fixes a corner case of fatal SIGSYS being ignored since v5.15.
Along with the signal fix is a change to seccomp so that seeing
another syscall after a fatal filter result will cause seccomp to kill
the process harder.
Summary:
- Force HANDLER_EXIT even for SIGNAL_UNKILLABLE
- Make seccomp self-destruct after fatal filter results
- Update seccomp samples for easier behavioral demonstration"
* tag 'seccomp-v5.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
samples/seccomp: Adjust sample to also provide kill option
seccomp: Invalidate seccomp mode to catch death failures
signal: HANDLER_EXIT should clear SIGNAL_UNKILLABLE
Commit 7d2b5dd0bc ("sched/numa: Allow a floating imbalance between NUMA
nodes") allowed an imbalance between NUMA nodes such that communicating
tasks would not be pulled apart by the load balancer. This works fine when
there is a 1:1 relationship between LLC and node but can be suboptimal
for multiple LLCs if independent tasks prematurely use CPUs sharing cache.
Zen* has multiple LLCs per node with local memory channels and due to
the allowed imbalance, it's far harder to tune some workloads to run
optimally than it is on hardware that has 1 LLC per node. This patch
allows an imbalance to exist up to the point where LLCs should be balanced
between nodes.
On a Zen3 machine running STREAM parallelised with OMP to have on instance
per LLC the results and without binding, the results are
5.17.0-rc0 5.17.0-rc0
vanilla sched-numaimb-v6
MB/sec copy-16 162596.94 ( 0.00%) 580559.74 ( 257.05%)
MB/sec scale-16 136901.28 ( 0.00%) 374450.52 ( 173.52%)
MB/sec add-16 157300.70 ( 0.00%) 564113.76 ( 258.62%)
MB/sec triad-16 151446.88 ( 0.00%) 564304.24 ( 272.61%)
STREAM can use directives to force the spread if the OpenMP is new
enough but that doesn't help if an application uses threads and
it's not known in advance how many threads will be created.
Coremark is a CPU and cache intensive benchmark parallelised with
threads. When running with 1 thread per core, the vanilla kernel
allows threads to contend on cache. With the patch;
5.17.0-rc0 5.17.0-rc0
vanilla sched-numaimb-v5
Min Score-16 368239.36 ( 0.00%) 389816.06 ( 5.86%)
Hmean Score-16 388607.33 ( 0.00%) 427877.08 * 10.11%*
Max Score-16 408945.69 ( 0.00%) 481022.17 ( 17.62%)
Stddev Score-16 15247.04 ( 0.00%) 24966.82 ( -63.75%)
CoeffVar Score-16 3.92 ( 0.00%) 5.82 ( -48.48%)
It can also make a big difference for semi-realistic workloads
like specjbb which can execute arbitrary numbers of threads without
advance knowledge of how they should be placed. Even in cases where
the average performance is neutral, the results are more stable.
5.17.0-rc0 5.17.0-rc0
vanilla sched-numaimb-v6
Hmean tput-1 71631.55 ( 0.00%) 73065.57 ( 2.00%)
Hmean tput-8 582758.78 ( 0.00%) 556777.23 ( -4.46%)
Hmean tput-16 1020372.75 ( 0.00%) 1009995.26 ( -1.02%)
Hmean tput-24 1416430.67 ( 0.00%) 1398700.11 ( -1.25%)
Hmean tput-32 1687702.72 ( 0.00%) 1671357.04 ( -0.97%)
Hmean tput-40 1798094.90 ( 0.00%) 2015616.46 * 12.10%*
Hmean tput-48 1972731.77 ( 0.00%) 2333233.72 ( 18.27%)
Hmean tput-56 2386872.38 ( 0.00%) 2759483.38 ( 15.61%)
Hmean tput-64 2909475.33 ( 0.00%) 2925074.69 ( 0.54%)
Hmean tput-72 2585071.36 ( 0.00%) 2962443.97 ( 14.60%)
Hmean tput-80 2994387.24 ( 0.00%) 3015980.59 ( 0.72%)
Hmean tput-88 3061408.57 ( 0.00%) 3010296.16 ( -1.67%)
Hmean tput-96 3052394.82 ( 0.00%) 2784743.41 ( -8.77%)
Hmean tput-104 2997814.76 ( 0.00%) 2758184.50 ( -7.99%)
Hmean tput-112 2955353.29 ( 0.00%) 2859705.09 ( -3.24%)
Hmean tput-120 2889770.71 ( 0.00%) 2764478.46 ( -4.34%)
Hmean tput-128 2871713.84 ( 0.00%) 2750136.73 ( -4.23%)
Stddev tput-1 5325.93 ( 0.00%) 2002.53 ( 62.40%)
Stddev tput-8 6630.54 ( 0.00%) 10905.00 ( -64.47%)
Stddev tput-16 25608.58 ( 0.00%) 6851.16 ( 73.25%)
Stddev tput-24 12117.69 ( 0.00%) 4227.79 ( 65.11%)
Stddev tput-32 27577.16 ( 0.00%) 8761.05 ( 68.23%)
Stddev tput-40 59505.86 ( 0.00%) 2048.49 ( 96.56%)
Stddev tput-48 168330.30 ( 0.00%) 93058.08 ( 44.72%)
Stddev tput-56 219540.39 ( 0.00%) 30687.02 ( 86.02%)
Stddev tput-64 121750.35 ( 0.00%) 9617.36 ( 92.10%)
Stddev tput-72 223387.05 ( 0.00%) 34081.13 ( 84.74%)
Stddev tput-80 128198.46 ( 0.00%) 22565.19 ( 82.40%)
Stddev tput-88 136665.36 ( 0.00%) 27905.97 ( 79.58%)
Stddev tput-96 111925.81 ( 0.00%) 99615.79 ( 11.00%)
Stddev tput-104 146455.96 ( 0.00%) 28861.98 ( 80.29%)
Stddev tput-112 88740.49 ( 0.00%) 58288.23 ( 34.32%)
Stddev tput-120 186384.86 ( 0.00%) 45812.03 ( 75.42%)
Stddev tput-128 78761.09 ( 0.00%) 57418.48 ( 27.10%)
Similarly, for embarassingly parallel problems like NPB-ep, there are
improvements due to better spreading across LLC when the machine is not
fully utilised.
vanilla sched-numaimb-v6
Min ep.D 31.79 ( 0.00%) 26.11 ( 17.87%)
Amean ep.D 31.86 ( 0.00%) 26.17 * 17.86%*
Stddev ep.D 0.07 ( 0.00%) 0.05 ( 24.41%)
CoeffVar ep.D 0.22 ( 0.00%) 0.20 ( 7.97%)
Max ep.D 31.93 ( 0.00%) 26.21 ( 17.91%)
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20220208094334.16379-3-mgorman@techsingularity.net
There are inconsistencies when determining if a NUMA imbalance is allowed
that should be corrected.
o allow_numa_imbalance changes types and is not always examining
the destination group so both the type should be corrected as
well as the naming.
o find_idlest_group uses the sched_domain's weight instead of the
group weight which is different to find_busiest_group
o find_busiest_group uses the source group instead of the destination
which is different to task_numa_find_cpu
o Both find_idlest_group and find_busiest_group should account
for the number of running tasks if a move was allowed to be
consistent with task_numa_find_cpu
Fixes: 7d2b5dd0bc ("sched/numa: Allow a floating imbalance between NUMA nodes")
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Gautham R. Shenoy <gautham.shenoy@amd.com>
Link: https://lore.kernel.org/r/20220208094334.16379-2-mgorman@techsingularity.net
A kernel exception was hit when trying to dump /proc/lockdep_chains after
lockdep report "BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!":
Unable to handle kernel paging request at virtual address 00054005450e05c3
...
00054005450e05c3] address between user and kernel address ranges
...
pc : [0xffffffece769b3a8] string+0x50/0x10c
lr : [0xffffffece769ac88] vsnprintf+0x468/0x69c
...
Call trace:
string+0x50/0x10c
vsnprintf+0x468/0x69c
seq_printf+0x8c/0xd8
print_name+0x64/0xf4
lc_show+0xb8/0x128
seq_read_iter+0x3cc/0x5fc
proc_reg_read_iter+0xdc/0x1d4
The cause of the problem is the function lock_chain_get_class() will
shift lock_classes index by 1, but the index don't need to be shifted
anymore since commit 01bb6f0af9 ("locking/lockdep: Change the range
of class_idx in held_lock struct") already change the index to start
from 0.
The lock_classes[-1] located at chain_hlocks array. When printing
lock_classes[-1] after the chain_hlocks entries are modified, the
exception happened.
The output of lockdep_chains are incorrect due to this problem too.
Fixes: f611e8cf98 ("lockdep: Take read/write status in consideration when generate chainkey")
Signed-off-by: Cheng Jui Wang <cheng-jui.wang@mediatek.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Link: https://lore.kernel.org/r/20220210105011.21712-1-cheng-jui.wang@mediatek.com
Currently the following code in check_and_init_map_value()
*(struct bpf_timer *)(dst + map->timer_off) =
(struct bpf_timer){};
can help generate bpf_timer definition in vmlinuxBTF.
But the code above may not zero the whole structure
due to anonymour members and that code will be replaced
by memset in the subsequent patch and
bpf_timer definition will disappear from vmlinuxBTF.
Let us emit the type explicitly so bpf program can continue
to use it from vmlinux.h.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220211194948.3141529-1-yhs@fb.com
Pull ACPI fixes from Rafael Wysocki:
"These revert two commits that turned out to be problematic and fix two
issues related to wakeup from suspend-to-idle on x86.
Specifics:
- Revert a recent change that attempted to avoid issues with
conflicting address ranges during PCI initialization, because it
turned out to introduce a regression (Hans de Goede).
- Revert a change that limited EC GPE wakeups from suspend-to-idle to
systems based on Intel hardware, because it turned out that systems
based on hardware from other vendors depended on that functionality
too (Mario Limonciello).
- Fix two issues related to the handling of wakeup interrupts and
wakeup events signaled through the EC GPE during suspend-to-idle on
x86 (Rafael Wysocki)"
* tag 'acpi-5.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
x86/PCI: revert "Ignore E820 reservations for bridge windows on newer systems"
PM: s2idle: ACPI: Fix wakeup interrupts handling
ACPI: PM: s2idle: Cancel wakeup before dispatching EC GPE
ACPI: PM: Revert "Only mark EC GPE for wakeup on Intel systems"
Pull tracing fixes from Steven Rostedt:
- Fixes to the RTLA tooling
- A fix to a tp_printk overriding tp_printk_stop_on_boot on the
command line
* tag 'trace-v5.17-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Fix tp_printk option related with tp_printk_stop_on_boot
MAINTAINERS: Add RTLA entry
rtla: Fix segmentation fault when failing to enable -t
rtla/trace: Error message fixup
rtla/utils: Fix session duration parsing
rtla: Follow kernel version
