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2025-02-19cgroup/dmem: Don't open-code css_for_each_descendant_preFriedrich Vock
The current implementation has a bug: If the current css doesn't contain any pool that is a descendant of the "pool" (i.e. when found_descendant == false), then "pool" will point to some unrelated pool. If the current css has a child, we'll overwrite parent_pool with this unrelated pool on the next iteration. Since we can just check whether a pool refers to the same region to determine whether or not it's related, all the additional pool tracking is unnecessary, so just switch to using css_for_each_descendant_pre for traversal. Fixes: b168ed458dde ("kernel/cgroup: Add "dmem" memory accounting cgroup") Signed-off-by: Friedrich Vock <friedrich.vock@gmx.de> Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20250127152754.21325-1-friedrich.vock@gmx.de Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
2025-01-23Merge v6.13 into drm-nextSimona Vetter
A regression was caused by commit e4b5ccd392b9 ("drm/v3d: Ensure job pointer is set to NULL after job completion"), but this commit is not yet in next-fixes, fast-forward it. Note that this recreates Linus merge in 96c84703f1cf ("Merge tag 'drm-next-2025-01-17' of https://gitlab.freedesktop.org/drm/kernel") because I didn't want to backmerge a random point in the merge window. Signed-off-by: Simona Vetter <simona.vetter@ffwll.ch>
2025-01-19Merge tag 'timers_urgent_for_v6.13' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull timer fixes from Borislav Petkov: - Reset hrtimers correctly when a CPU hotplug state traversal happens "half-ways" and leaves hrtimers not (re-)initialized properly - Annotate accesses to a timer group's ignore flag to prevent KCSAN from raising data_race warnings - Make sure timer group initialization is visible to timer tree walkers and avoid a hypothetical race - Fix another race between CPU hotplug and idle entry/exit where timers on a fully idle system are getting ignored - Fix a case where an ignored signal is still being handled which it shouldn't be * tag 'timers_urgent_for_v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: hrtimers: Handle CPU state correctly on hotplug timers/migration: Annotate accesses to ignore flag timers/migration: Enforce group initialization visibility to tree walkers timers/migration: Fix another race between hotplug and idle entry/exit signal/posixtimers: Handle ignore/blocked sequences correctly
2025-01-19Merge tag 'sched_urgent_for_v6.13' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Borislav Petkov: - Do not adjust the weight of empty group entities and avoid scheduling artifacts - Avoid scheduling lag by computing lag properly and thus address an EEVDF entity placement issue * tag 'sched_urgent_for_v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/fair: Fix update_cfs_group() vs DELAY_DEQUEUE sched/fair: Fix EEVDF entity placement bug causing scheduling lag
2025-01-16hrtimers: Handle CPU state correctly on hotplugKoichiro Den
Consider a scenario where a CPU transitions from CPUHP_ONLINE to halfway through a CPU hotunplug down to CPUHP_HRTIMERS_PREPARE, and then back to CPUHP_ONLINE: Since hrtimers_prepare_cpu() does not run, cpu_base.hres_active remains set to 1 throughout. However, during a CPU unplug operation, the tick and the clockevents are shut down at CPUHP_AP_TICK_DYING. On return to the online state, for instance CFS incorrectly assumes that the hrtick is already active, and the chance of the clockevent device to transition to oneshot mode is also lost forever for the CPU, unless it goes back to a lower state than CPUHP_HRTIMERS_PREPARE once. This round-trip reveals another issue; cpu_base.online is not set to 1 after the transition, which appears as a WARN_ON_ONCE in enqueue_hrtimer(). Aside of that, the bulk of the per CPU state is not reset either, which means there are dangling pointers in the worst case. Address this by adding a corresponding startup() callback, which resets the stale per CPU state and sets the online flag. [ tglx: Make the new callback unconditionally available, remove the online modification in the prepare() callback and clear the remaining state in the starting callback instead of the prepare callback ] Fixes: 5c0930ccaad5 ("hrtimers: Push pending hrtimers away from outgoing CPU earlier") Signed-off-by: Koichiro Den <koichiro.den@canonical.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/20241220134421.3809834-1-koichiro.den@canonical.com
2025-01-16timers/migration: Annotate accesses to ignore flagFrederic Weisbecker
The group's ignore flag is: _ read under the group's lock (idle entry, remote expiry) _ turned on/off under the group's lock (idle entry, remote expiry) _ turned on locklessly on idle exit When idle entry or remote expiry clear the "ignore" flag of a group, the operation must be synchronized against other concurrent idle entry or remote expiry to make sure the related group timer is never missed. To enforce this synchronization, both "ignore" clear and read are performed under the group lock. On the contrary, whether idle entry or remote expiry manage to observe the "ignore" flag turned on by a CPU exiting idle is a matter of optimization. If that flag set is missed or cleared concurrently, the worst outcome is a migrator wasting time remotely handling a "ghost" timer. This is why the ignore flag can be set locklessly. Unfortunately, the related lockless accesses are bare and miss appropriate annotations. KCSAN rightfully complains: BUG: KCSAN: data-race in __tmigr_cpu_activate / print_report write to 0xffff88842fc28004 of 1 bytes by task 0 on cpu 0: __tmigr_cpu_activate tmigr_cpu_activate timer_clear_idle tick_nohz_restart_sched_tick tick_nohz_idle_exit do_idle cpu_startup_entry kernel_init do_initcalls clear_bss reserve_bios_regions common_startup_64 read to 0xffff88842fc28004 of 1 bytes by task 0 on cpu 1: print_report kcsan_report_known_origin kcsan_setup_watchpoint tmigr_next_groupevt tmigr_update_events tmigr_inactive_up __walk_groups+0x50/0x77 walk_groups __tmigr_cpu_deactivate tmigr_cpu_deactivate __get_next_timer_interrupt timer_base_try_to_set_idle tick_nohz_stop_tick tick_nohz_idle_stop_tick cpuidle_idle_call do_idle Although the relevant accesses could be marked as data_race(), the "ignore" flag being read several times within the same tmigr_update_events() function is confusing and error prone. Prefer reading it once in that function and make use of similar/paired accesses elsewhere with appropriate comments when necessary. Reported-by: kernel test robot <oliver.sang@intel.com> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/all/20250114231507.21672-4-frederic@kernel.org Closes: https://lore.kernel.org/oe-lkp/202501031612.62e0c498-lkp@intel.com
2025-01-16timers/migration: Enforce group initialization visibility to tree walkersFrederic Weisbecker
Commit 2522c84db513 ("timers/migration: Fix another race between hotplug and idle entry/exit") fixed yet another race between idle exit and CPU hotplug up leading to a wrong "0" value migrator assigned to the top level. However there is yet another situation that remains unhandled: [GRP0:0] migrator = TMIGR_NONE active = NONE groupmask = 1 / \ \ 0 1 2..7 idle idle idle 0) The system is fully idle. [GRP0:0] migrator = CPU 0 active = CPU 0 groupmask = 1 / \ \ 0 1 2..7 active idle idle 1) CPU 0 is activating. It has done the cmpxchg on the top's ->migr_state but it hasn't yet returned to __walk_groups(). [GRP0:0] migrator = CPU 0 active = CPU 0, CPU 1 groupmask = 1 / \ \ 0 1 2..7 active active idle 2) CPU 1 is activating. CPU 0 stays the migrator (still stuck in __walk_groups(), delayed by #VMEXIT for example). [GRP1:0] migrator = TMIGR_NONE active = NONE groupmask = 1 / \ [GRP0:0] [GRP0:1] migrator = CPU 0 migrator = TMIGR_NONE active = CPU 0, CPU1 active = NONE groupmask = 1 groupmask = 2 / \ \ 0 1 2..7 8 active active idle !online 3) CPU 8 is preparing to boot. CPUHP_TMIGR_PREPARE is being ran by CPU 1 which has created the GRP0:1 and the new top GRP1:0 connected to GRP0:1 and GRP0:0. CPU 1 hasn't yet propagated its activation up to GRP1:0. [GRP1:0] migrator = GRP0:0 active = GRP0:0 groupmask = 1 / \ [GRP0:0] [GRP0:1] migrator = CPU 0 migrator = TMIGR_NONE active = CPU 0, CPU1 active = NONE groupmask = 1 groupmask = 2 / \ \ 0 1 2..7 8 active active idle !online 4) CPU 0 finally resumed after its #VMEXIT. It's in __walk_groups() returning from tmigr_cpu_active(). The new top GRP1:0 is visible and fetched and the pre-initialized groupmask of GRP0:0 is also visible. As a result tmigr_active_up() is called to GRP1:0 with GRP0:0 as active and migrator. CPU 0 is returning to __walk_groups() but suffers again a #VMEXIT. [GRP1:0] migrator = GRP0:0 active = GRP0:0 groupmask = 1 / \ [GRP0:0] [GRP0:1] migrator = CPU 0 migrator = TMIGR_NONE active = CPU 0, CPU1 active = NONE groupmask = 1 groupmask = 2 / \ \ 0 1 2..7 8 active active idle !online 5) CPU 1 propagates its activation of GRP0:0 to GRP1:0. This has no effect since CPU 0 did it already. [GRP1:0] migrator = GRP0:0 active = GRP0:0, GRP0:1 groupmask = 1 / \ [GRP0:0] [GRP0:1] migrator = CPU 0 migrator = CPU 8 active = CPU 0, CPU1 active = CPU 8 groupmask = 1 groupmask = 2 / \ \ \ 0 1 2..7 8 active active idle active 6) CPU 1 links CPU 8 to its group. CPU 8 boots and goes through CPUHP_AP_TMIGR_ONLINE which propagates activation. [GRP2:0] migrator = TMIGR_NONE active = NONE groupmask = 1 / \ [GRP1:0] [GRP1:1] migrator = GRP0:0 migrator = TMIGR_NONE active = GRP0:0, GRP0:1 active = NONE groupmask = 1 groupmask = 2 / \ [GRP0:0] [GRP0:1] [GRP0:2] migrator = CPU 0 migrator = CPU 8 migrator = TMIGR_NONE active = CPU 0, CPU1 active = CPU 8 active = NONE groupmask = 1 groupmask = 2 groupmask = 0 / \ \ \ 0 1 2..7 8 64 active active idle active !online 7) CPU 64 is booting. CPUHP_TMIGR_PREPARE is being ran by CPU 1 which has created the GRP1:1, GRP0:2 and the new top GRP2:0 connected to GRP1:1 and GRP1:0. CPU 1 hasn't yet propagated its activation up to GRP2:0. [GRP2:0] migrator = 0 (!!!) active = NONE groupmask = 1 / \ [GRP1:0] [GRP1:1] migrator = GRP0:0 migrator = TMIGR_NONE active = GRP0:0, GRP0:1 active = NONE groupmask = 1 groupmask = 2 / \ [GRP0:0] [GRP0:1] [GRP0:2] migrator = CPU 0 migrator = CPU 8 migrator = TMIGR_NONE active = CPU 0, CPU1 active = CPU 8 active = NONE groupmask = 1 groupmask = 2 groupmask = 0 / \ \ \ 0 1 2..7 8 64 active active idle active !online 8) CPU 0 finally resumed after its #VMEXIT. It's in __walk_groups() returning from tmigr_cpu_active(). The new top GRP2:0 is visible and fetched but the pre-initialized groupmask of GRP1:0 is not because no ordering made its initialization visible. As a result tmigr_active_up() may be called to GRP2:0 with a "0" child's groumask. Leaving the timers ignored for ever when the system is fully idle. The race is highly theoretical and perhaps impossible in practice but the groupmask of the child is not the only concern here as the whole initialization of the child is not guaranteed to be visible to any tree walker racing against hotplug (idle entry/exit, remote handling, etc...). Although the current code layout seem to be resilient to such hazards, this doesn't tell much about the future. Fix this with enforcing address dependency between group initialization and the write/read to the group's parent's pointer. Fortunately that doesn't involve any barrier addition in the fast paths. Fixes: 10a0e6f3d3db ("timers/migration: Move hierarchy setup into cpuhotplug prepare callback") Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/20250114231507.21672-3-frederic@kernel.org
2025-01-16timers/migration: Fix another race between hotplug and idle entry/exitFrederic Weisbecker
Commit 10a0e6f3d3db ("timers/migration: Move hierarchy setup into cpuhotplug prepare callback") fixed a race between idle exit and CPU hotplug up leading to a wrong "0" value migrator assigned to the top level. However there is still a situation that remains unhandled: [GRP0:0] migrator = TMIGR_NONE active = NONE groupmask = 0 / \ \ 0 1 2..7 idle idle idle 0) The system is fully idle. [GRP0:0] migrator = CPU 0 active = CPU 0 groupmask = 0 / \ \ 0 1 2..7 active idle idle 1) CPU 0 is activating. It has done the cmpxchg on the top's ->migr_state but it hasn't yet returned to __walk_groups(). [GRP0:0] migrator = CPU 0 active = CPU 0, CPU 1 groupmask = 0 / \ \ 0 1 2..7 active active idle 2) CPU 1 is activating. CPU 0 stays the migrator (still stuck in __walk_groups(), delayed by #VMEXIT for example). [GRP1:0] migrator = TMIGR_NONE active = NONE groupmask = 0 / \ [GRP0:0] [GRP0:1] migrator = CPU 0 migrator = TMIGR_NONE active = CPU 0, CPU1 active = NONE groupmask = 2 groupmask = 1 / \ \ 0 1 2..7 8 active active idle !online 3) CPU 8 is preparing to boot. CPUHP_TMIGR_PREPARE is being ran by CPU 1 which has created the GRP0:1 and the new top GRP1:0 connected to GRP0:1 and GRP0:0. The groupmask of GRP0:0 is now 2. CPU 1 hasn't yet propagated its activation up to GRP1:0. [GRP1:0] migrator = 0 (!!!) active = NONE groupmask = 0 / \ [GRP0:0] [GRP0:1] migrator = CPU 0 migrator = TMIGR_NONE active = CPU 0, CPU1 active = NONE groupmask = 2 groupmask = 1 / \ \ 0 1 2..7 8 active active idle !online 4) CPU 0 finally resumed after its #VMEXIT. It's in __walk_groups() returning from tmigr_cpu_active(). The new top GRP1:0 is visible and fetched but the freshly updated groupmask of GRP0:0 may not be visible due to lack of ordering! As a result tmigr_active_up() is called to GRP0:0 with a child's groupmask of "0". This buggy "0" groupmask then becomes the migrator for GRP1:0 forever. As a result, timers on a fully idle system get ignored. One possible fix would be to define TMIGR_NONE as "0" so that such a race would have no effect. And after all TMIGR_NONE doesn't need to be anything else. However this would leave an uncomfortable state machine where gears happen not to break by chance but are vulnerable to future modifications. Keep TMIGR_NONE as is instead and pre-initialize to "1" the groupmask of any newly created top level. This groupmask is guaranteed to be visible upon fetching the corresponding group for the 1st time: _ By the upcoming CPU thanks to CPU hotplug synchronization between the control CPU (BP) and the booting one (AP). _ By the control CPU since the groupmask and parent pointers are initialized locally. _ By all CPUs belonging to the same group than the control CPU because they must wait for it to ever become idle before needing to walk to the new top. The cmpcxhg() on ->migr_state then makes sure its groupmask is visible. With this pre-initialization, it is guaranteed that if a future top level is linked to an old one, it is walked through with a valid groupmask. Fixes: 10a0e6f3d3db ("timers/migration: Move hierarchy setup into cpuhotplug prepare callback") Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/all/20250114231507.21672-2-frederic@kernel.org
2025-01-15signal/posixtimers: Handle ignore/blocked sequences correctlyThomas Gleixner
syzbot triggered the warning in posixtimer_send_sigqueue(), which warns about a non-ignored signal being already queued on the ignored list. The warning is actually bogus, as the following sequence causes this: signal($SIG, SIGIGN); timer_settime(...); // arm periodic timer timer fires, signal is ignored and queued on ignored list sigprocmask(SIG_BLOCK, ...); // block the signal timer_settime(...); // re-arm periodic timer timer fires, signal is not ignored because it is blocked ---> Warning triggers as signal is on the ignored list Ideally timer_settime() could remove the signal, but that's racy and incomplete vs. other scenarios and requires a full reevaluation of the pending signal list. Instead of adding more complexity, handle it gracefully by removing the warning and requeueing the signal to the pending list. That's correct versus: 1) sig[timed]wait() as that does not check for SIGIGN and only relies on dequeue_signal() -> posixtimers_deliver_signal() to check whether the pending signal is still valid. 2) Unblocking of the signal. - If the unblocking happens before SIGIGN is replaced by a signal handler, then the timer is rearmed in dequeue_signal(), but get_signal() will ignore it. The next timer expiry will move it back to the ignored list. - If SIGIGN was replaced before unblocking, then the signal will be delivered and a subsequent expiry will queue a signal on the pending list again. There is a related scenario to trigger the complementary warning in the signal ignored path, which does not expect the signal to be on the pending list when it is ignored. That can be triggered even before the above change via: task1 task2 signal($SIG, SIGIGN); sigprocmask(SIG_BLOCK, ...); timer_create(); // Signal target is task2 timer_settime(...); // arm periodic timer timer fires, signal is not ignored because it is blocked and queued on the pending list of task2 syscall() // Sets the pending flag sigprocmask(SIG_UNBLOCK, ...); -> preemption, task2 cannot dequeue the signal timer_settime(...); // re-arm periodic timer timer fires, signal is ignored ---> Warning triggers as signal is on task2's pending list and the thread group is not exiting Consequently, remove that warning too and just keep the signal on the pending list. The following attempt to deliver the signal on return to user space of task2 will ignore the signal and a subsequent expiry will bring it back to the ignored list, if it did not get blocked or un-ignored before that. Fixes: df7a996b4dab ("signal: Queue ignored posixtimers on ignore list") Reported-by: syzbot+3c2e3cc60665d71de2f7@syzkaller.appspotmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lore.kernel.org/all/87ikqhcnjn.ffs@tglx
2025-01-15cgroup/dmem: Fix parameters documentationMaxime Ripard
During the dmem cgroup development, the parameters to the dmem_cgroup_state_evict_valuable() and dmem_cgroup_try_charge() were changed, but the documentation wasn't adjusted accordingly. This results in a documentation build warning. Adjust the documentation to reflect what the final functions parameters are. Fixes: b168ed458dde ("kernel/cgroup: Add "dmem" memory accounting cgroup") Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Closes: https://lore.kernel.org/r/20250113160334.1f09f881@canb.auug.org.au/ Acked-by: Tejun Heo <tj@kernel.org> Reviewed-by: Simona Vetter <simona.vetter@ffwll.ch> Link: https://patchwork.freedesktop.org/patch/msgid/20250113092608.1349287-2-mripard@kernel.org Signed-off-by: Maxime Ripard <mripard@kernel.org>
2025-01-15kernel/cgroup: Remove the unused variable climitJiapeng Chong
Variable climit is not effectively used, so delete it. kernel/cgroup/dmem.c:302:23: warning: variable ‘climit’ set but not used. Reported-by: Abaci Robot <abaci@linux.alibaba.com> Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=13512 Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com> Acked-by: Tejun Heo <tj@kernel.org> Link: https://patchwork.freedesktop.org/patch/msgid/20250114062804.5092-1-jiapeng.chong@linux.alibaba.com Signed-off-by: Maxime Ripard <mripard@kernel.org>
2025-01-14tracing: Print lazy preemption modelShrikanth Hegde
Print lazy preemption model in ftrace header when latency-format=1. # cat /sys/kernel/debug/sched/preempt none voluntary full (lazy) Without patch: latency: 0 us, #232946/232946, CPU#40 | (M:unknown VP:0, KP:0, SP:0 HP:0 #P:80) ^^^^^^^ With Patch: latency: 0 us, #1897938/25566788, CPU#16 | (M:lazy VP:0, KP:0, SP:0 HP:0 #P:80) ^^^^ Now that lazy preemption is part of the kernel, make sure the tracing infrastructure reflects that. Link: https://lore.kernel.org/20250103093647.575919-1-sshegde@linux.ibm.com Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com> Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-01-14tracing: Fix irqsoff and wakeup latency tracers when using function graphSteven Rostedt
The function graph tracer has become generic so that kretprobes and BPF can use it along with function graph tracing itself. Some of the infrastructure was specific for function graph tracing such as recording the calltime and return time of the functions. Calling the clock code on a high volume function does add overhead. The calculation of the calltime was removed from the generic code and placed into the function graph tracer itself so that the other users did not incur this overhead as they did not need that timestamp. The calltime field was still kept in the generic return entry structure and the function graph return entry callback filled it as that structure was passed to other code. But this broke both irqsoff and wakeup latency tracer as they still depended on the trace structure containing the calltime when the option display-graph is set as it used some of those same functions that the function graph tracer used. But now the calltime was not set and was just zero. This caused the calculation of the function time to be the absolute value of the return timestamp and not the length of the function. # cd /sys/kernel/tracing # echo 1 > options/display-graph # echo irqsoff > current_tracer The tracers went from: # REL TIME CPU TASK/PID |||| DURATION FUNCTION CALLS # | | | | |||| | | | | | | 0 us | 4) <idle>-0 | d..1. | 0.000 us | irqentry_enter(); 3 us | 4) <idle>-0 | d..2. | | irq_enter_rcu() { 4 us | 4) <idle>-0 | d..2. | 0.431 us | preempt_count_add(); 5 us | 4) <idle>-0 | d.h2. | | tick_irq_enter() { 5 us | 4) <idle>-0 | d.h2. | 0.433 us | tick_check_oneshot_broadcast_this_cpu(); 6 us | 4) <idle>-0 | d.h2. | 2.426 us | ktime_get(); 9 us | 4) <idle>-0 | d.h2. | | tick_nohz_stop_idle() { 10 us | 4) <idle>-0 | d.h2. | 0.398 us | nr_iowait_cpu(); 11 us | 4) <idle>-0 | d.h1. | 1.903 us | } 11 us | 4) <idle>-0 | d.h2. | | tick_do_update_jiffies64() { 12 us | 4) <idle>-0 | d.h2. | | _raw_spin_lock() { 12 us | 4) <idle>-0 | d.h2. | 0.360 us | preempt_count_add(); 13 us | 4) <idle>-0 | d.h3. | 0.354 us | do_raw_spin_lock(); 14 us | 4) <idle>-0 | d.h2. | 2.207 us | } 15 us | 4) <idle>-0 | d.h3. | 0.428 us | calc_global_load(); 16 us | 4) <idle>-0 | d.h3. | | _raw_spin_unlock() { 16 us | 4) <idle>-0 | d.h3. | 0.380 us | do_raw_spin_unlock(); 17 us | 4) <idle>-0 | d.h3. | 0.334 us | preempt_count_sub(); 18 us | 4) <idle>-0 | d.h1. | 1.768 us | } 18 us | 4) <idle>-0 | d.h2. | | update_wall_time() { [..] To: # REL TIME CPU TASK/PID |||| DURATION FUNCTION CALLS # | | | | |||| | | | | | | 0 us | 5) <idle>-0 | d.s2. | 0.000 us | _raw_spin_lock_irqsave(); 0 us | 5) <idle>-0 | d.s3. | 312159583 us | preempt_count_add(); 2 us | 5) <idle>-0 | d.s4. | 312159585 us | do_raw_spin_lock(); 3 us | 5) <idle>-0 | d.s4. | | _raw_spin_unlock() { 3 us | 5) <idle>-0 | d.s4. | 312159586 us | do_raw_spin_unlock(); 4 us | 5) <idle>-0 | d.s4. | 312159587 us | preempt_count_sub(); 4 us | 5) <idle>-0 | d.s2. | 312159587 us | } 5 us | 5) <idle>-0 | d.s3. | | _raw_spin_lock() { 5 us | 5) <idle>-0 | d.s3. | 312159588 us | preempt_count_add(); 6 us | 5) <idle>-0 | d.s4. | 312159589 us | do_raw_spin_lock(); 7 us | 5) <idle>-0 | d.s3. | 312159590 us | } 8 us | 5) <idle>-0 | d.s4. | 312159591 us | calc_wheel_index(); 9 us | 5) <idle>-0 | d.s4. | | enqueue_timer() { 9 us | 5) <idle>-0 | d.s4. | | wake_up_nohz_cpu() { 11 us | 5) <idle>-0 | d.s4. | | native_smp_send_reschedule() { 11 us | 5) <idle>-0 | d.s4. | 312171987 us | default_send_IPI_single_phys(); 12408 us | 5) <idle>-0 | d.s3. | 312171990 us | } 12408 us | 5) <idle>-0 | d.s3. | 312171991 us | } 12409 us | 5) <idle>-0 | d.s3. | 312171991 us | } Where the calculation of the time for each function was the return time minus zero and not the time of when the function returned. Have these tracers also save the calltime in the fgraph data section and retrieve it again on the return to get the correct timings again. Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Mark Rutland <mark.rutland@arm.com> Link: https://lore.kernel.org/20250113183124.61767419@gandalf.local.home Fixes: f1f36e22bee9 ("ftrace: Have calltime be saved in the fgraph storage") Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-01-13sched/fair: Fix update_cfs_group() vs DELAY_DEQUEUEPeter Zijlstra
Normally dequeue_entities() will continue to dequeue an empty group entity; except DELAY_DEQUEUE changes things -- it retains empty entities such that they might continue to compete and burn off some lag. However, doing this results in update_cfs_group() re-computing the cgroup weight 'slice' for an empty group, which it (rightly) figures isn't much at all. This in turn means that the delayed entity is not competing at the expected weight. Worse, the very low weight causes its lag to be inflated, which combined with avg_vruntime() using scale_load_down(), leads to artifacts. As such, don't adjust the weight for empty group entities and let them compete at their original weight. Fixes: 152e11f6df29 ("sched/fair: Implement delayed dequeue") Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20250110115720.GA17405@noisy.programming.kicks-ass.net
2025-01-12Merge tag 'perf_urgent_for_v6.13_rc7' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull perf fix from Borislav Petkov: - Fix a #GP in the perf user callchain code caused by a race between uprobe freeing the task and the bpf profiler unwinding the task's user stack * tag 'perf_urgent_for_v6.13_rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: uprobes: Fix race in uprobe_free_utask
2025-01-11Merge tag 'probes-fixes-v6.13-rc6' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull probes fix from Masami Hiramatsu: "Fix to free trace_kprobe objects at a failure path in __trace_kprobe_create() function. This fixes a memory leak" * tag 'probes-fixes-v6.13-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: tracing/kprobes: Fix to free objects when failed to copy a symbol
2025-01-10Merge tag 'sched_ext-for-6.13-rc6-fixes' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext Pull sched_ext fixes from Tejun Heo: - Fix corner case bug where ops.dispatch() couldn't extend the execution of the current task if SCX_OPS_ENQ_LAST is set. - Fix ops.cpu_release() not being called when a SCX task is preempted by a higher priority sched class task. - Fix buitin idle mask being incorrectly left as busy after an idle CPU is picked and kicked. - scx_ops_bypass() was unnecessarily using rq_lock() which comes with rq pinning related sanity checks which could trigger spuriously. Switch to raw_spin_rq_lock(). * tag 'sched_ext-for-6.13-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext: sched_ext: idle: Refresh idle masks during idle-to-idle transitions sched_ext: switch class when preempted by higher priority scheduler sched_ext: Replace rq_lock() to raw_spin_rq_lock() in scx_ops_bypass() sched_ext: keep running prev when prev->scx.slice != 0
2025-01-10Merge tag 'cgroup-for-6.13-rc6-fixes' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup fixes from Tejun Heo: "Cpuset fixes: - Fix isolated CPUs leaking into sched domains - Remove now unnecessary kernfs active break which can trigger a warning - Comment updates" * tag 'cgroup-for-6.13-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup/cpuset: remove kernfs active break cgroup/cpuset: Prevent leakage of isolated CPUs into sched domains cgroup/cpuset: Remove stale text
2025-01-10Merge tag 'wq-for-6.13-rc6-fixes' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq Pull workqueue fix from Tejun Heo: - Add a WARN_ON_ONCE() on queue_delayed_work_on() on an offline CPU as such work items won't get executed till the CPU comes back online * tag 'wq-for-6.13-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: warn if delayed_work is queued to an offlined cpu.
2025-01-10sched_ext: idle: Refresh idle masks during idle-to-idle transitionsAndrea Righi
With the consolidation of put_prev_task/set_next_task(), see commit 436f3eed5c69 ("sched: Combine the last put_prev_task() and the first set_next_task()"), we are now skipping the transition between these two functions when the previous and the next tasks are the same. As a result, the scx idle state of a CPU is updated only when transitioning to or from the idle thread. While this is generally correct, it can lead to uneven and inefficient core utilization in certain scenarios [1]. A typical scenario involves proactive wake-ups: scx_bpf_pick_idle_cpu() selects and marks an idle CPU as busy, followed by a wake-up via scx_bpf_kick_cpu(), without dispatching any tasks. In this case, the CPU continues running the idle thread, returns to idle, but remains marked as busy, preventing it from being selected again as an idle CPU (until a task eventually runs on it and releases the CPU). For example, running a workload that uses 20% of each CPU, combined with an scx scheduler using proactive wake-ups, results in the following core utilization: CPU 0: 25.7% CPU 1: 29.3% CPU 2: 26.5% CPU 3: 25.5% CPU 4: 0.0% CPU 5: 25.5% CPU 6: 0.0% CPU 7: 10.5% To address this, refresh the idle state also in pick_task_idle(), during idle-to-idle transitions, but only trigger ops.update_idle() on actual state changes to prevent unnecessary updates to the scx scheduler and maintain balanced state transitions. With this change in place, the core utilization in the previous example becomes the following: CPU 0: 18.8% CPU 1: 19.4% CPU 2: 18.0% CPU 3: 18.7% CPU 4: 19.3% CPU 5: 18.9% CPU 6: 18.7% CPU 7: 19.3% [1] https://github.com/sched-ext/scx/pull/1139 Fixes: 7c65ae81ea86 ("sched_ext: Don't call put_prev_task_scx() before picking the next task") Signed-off-by: Andrea Righi <arighi@nvidia.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2025-01-10workqueue: warn if delayed_work is queued to an offlined cpu.Imran Khan
delayed_work submitted to an offlined cpu, will not get executed, after the specified delay if the cpu remains offline. If the cpu never comes online the work will never get executed. checking for online cpu in __queue_delayed_work, does not sound like a good idea because to do this reliably we need hotplug lock and since work may be submitted from atomic contexts, we would have to use cpus_read_trylock. But if trylock fails we would queue the work on any cpu and this may not be optimal because our intended cpu might still be online. Putting a WARN_ON_ONCE for an already offlined cpu, will indicate users of queue_delayed_work_on, if they are (wrongly) trying to queue delayed_work on offlined cpu. Also indicate the problem of using offlined cpu with queue_delayed_work_on, in its description. Signed-off-by: Imran Khan <imran.f.khan@oracle.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2025-01-10uprobes: Fix race in uprobe_free_utaskJiri Olsa
Max Makarov reported kernel panic [1] in perf user callchain code. The reason for that is the race between uprobe_free_utask and bpf profiler code doing the perf user stack unwind and is triggered within uprobe_free_utask function: - after current->utask is freed and - before current->utask is set to NULL general protection fault, probably for non-canonical address 0x9e759c37ee555c76: 0000 [#1] SMP PTI RIP: 0010:is_uprobe_at_func_entry+0x28/0x80 ... ? die_addr+0x36/0x90 ? exc_general_protection+0x217/0x420 ? asm_exc_general_protection+0x26/0x30 ? is_uprobe_at_func_entry+0x28/0x80 perf_callchain_user+0x20a/0x360 get_perf_callchain+0x147/0x1d0 bpf_get_stackid+0x60/0x90 bpf_prog_9aac297fb833e2f5_do_perf_event+0x434/0x53b ? __smp_call_single_queue+0xad/0x120 bpf_overflow_handler+0x75/0x110 ... asm_sysvec_apic_timer_interrupt+0x1a/0x20 RIP: 0010:__kmem_cache_free+0x1cb/0x350 ... ? uprobe_free_utask+0x62/0x80 ? acct_collect+0x4c/0x220 uprobe_free_utask+0x62/0x80 mm_release+0x12/0xb0 do_exit+0x26b/0xaa0 __x64_sys_exit+0x1b/0x20 do_syscall_64+0x5a/0x80 It can be easily reproduced by running following commands in separate terminals: # while :; do bpftrace -e 'uprobe:/bin/ls:_start { printf("hit\n"); }' -c ls; done # bpftrace -e 'profile:hz:100000 { @[ustack()] = count(); }' Fixing this by making sure current->utask pointer is set to NULL before we start to release the utask object. [1] https://github.com/grafana/pyroscope/issues/3673 Fixes: cfa7f3d2c526 ("perf,x86: avoid missing caller address in stack traces captured in uprobe") Reported-by: Max Makarov <maxpain@linux.com> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/r/20250109141440.2692173-1-jolsa@kernel.org
2025-01-10tracing/kprobes: Fix to free objects when failed to copy a symbolMasami Hiramatsu (Google)
In __trace_kprobe_create(), if something fails it must goto error block to free objects. But when strdup() a symbol, it returns without that. Fix it to goto the error block to free objects correctly. Link: https://lore.kernel.org/all/173643297743.1514810.2408159540454241947.stgit@devnote2/ Fixes: 6212dd29683e ("tracing/kprobes: Use dyn_event framework for kprobe events") Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org> Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-01-09sched/fair: Fix EEVDF entity placement bug causing scheduling lagPeter Zijlstra
I noticed this in my traces today: turbostat-1222 [006] d..2. 311.935649: reweight_entity: (ffff888108f13e00-ffff88885ef38440-6) { weight: 1048576 avg_vruntime: 3184159639071 vruntime: 3184159640194 (-1123) deadline: 3184162621107 } -> { weight: 2 avg_vruntime: 3184177463330 vruntime: 3184748414495 (-570951165) deadline: 4747605329439 } turbostat-1222 [006] d..2. 311.935651: reweight_entity: (ffff888108f13e00-ffff88885ef38440-6) { weight: 2 avg_vruntime: 3184177463330 vruntime: 3184748414495 (-570951165) deadline: 4747605329439 } -> { weight: 1048576 avg_vruntime: 3184176414812 vruntime: 3184177464419 (-1049607) deadline: 3184180445332 } Which is a weight transition: 1048576 -> 2 -> 1048576. One would expect the lag to shoot out *AND* come back, notably: -1123*1048576/2 = -588775424 -588775424*2/1048576 = -1123 Except the trace shows it is all off. Worse, subsequent cycles shoot it out further and further. This made me have a very hard look at reweight_entity(), and specifically the ->on_rq case, which is more prominent with DELAY_DEQUEUE. And indeed, it is all sorts of broken. While the computation of the new lag is correct, the computation for the new vruntime, using the new lag is broken for it does not consider the logic set out in place_entity(). With the below patch, I now see things like: migration/12-55 [012] d..3. 309.006650: reweight_entity: (ffff8881e0e6f600-ffff88885f235f40-12) { weight: 977582 avg_vruntime: 4860513347366 vruntime: 4860513347908 (-542) deadline: 4860516552475 } -> { weight: 2 avg_vruntime: 4860528915984 vruntime: 4860793840706 (-264924722) deadline: 6427157349203 } migration/14-62 [014] d..3. 309.006698: reweight_entity: (ffff8881e0e6cc00-ffff88885f3b5f40-15) { weight: 2 avg_vruntime: 4874472992283 vruntime: 4939833828823 (-65360836540) deadline: 6316614641111 } -> { weight: 967149 avg_vruntime: 4874217684324 vruntime: 4874217688559 (-4235) deadline: 4874220535650 } Which isn't perfect yet, but much closer. Reported-by: Doug Smythies <dsmythies@telus.net> Reported-by: Ingo Molnar <mingo@kernel.org> Tested-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Ingo Molnar <mingo@kernel.org> Fixes: eab03c23c2a1 ("sched/eevdf: Fix vruntime adjustment on reweight") Link: https://lore.kernel.org/r/20250109105959.GA2981@noisy.programming.kicks-ass.net
2025-01-08cgroup/cpuset: remove kernfs active breakChen Ridong
A warning was found: WARNING: CPU: 10 PID: 3486953 at fs/kernfs/file.c:828 CPU: 10 PID: 3486953 Comm: rmdir Kdump: loaded Tainted: G RIP: 0010:kernfs_should_drain_open_files+0x1a1/0x1b0 RSP: 0018:ffff8881107ef9e0 EFLAGS: 00010202 RAX: 0000000080000002 RBX: ffff888154738c00 RCX: dffffc0000000000 RDX: 0000000000000007 RSI: 0000000000000004 RDI: ffff888154738c04 RBP: ffff888154738c04 R08: ffffffffaf27fa15 R09: ffffed102a8e7180 R10: ffff888154738c07 R11: 0000000000000000 R12: ffff888154738c08 R13: ffff888750f8c000 R14: ffff888750f8c0e8 R15: ffff888154738ca0 FS: 00007f84cd0be740(0000) GS:ffff8887ddc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000555f9fbe00c8 CR3: 0000000153eec001 CR4: 0000000000370ee0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: kernfs_drain+0x15e/0x2f0 __kernfs_remove+0x165/0x300 kernfs_remove_by_name_ns+0x7b/0xc0 cgroup_rm_file+0x154/0x1c0 cgroup_addrm_files+0x1c2/0x1f0 css_clear_dir+0x77/0x110 kill_css+0x4c/0x1b0 cgroup_destroy_locked+0x194/0x380 cgroup_rmdir+0x2a/0x140 It can be explained by: rmdir echo 1 > cpuset.cpus kernfs_fop_write_iter // active=0 cgroup_rm_file kernfs_remove_by_name_ns kernfs_get_active // active=1 __kernfs_remove // active=0x80000002 kernfs_drain cpuset_write_resmask wait_event //waiting (active == 0x80000001) kernfs_break_active_protection // active = 0x80000001 // continue kernfs_unbreak_active_protection // active = 0x80000002 ... kernfs_should_drain_open_files // warning occurs kernfs_put_active This warning is caused by 'kernfs_break_active_protection' when it is writing to cpuset.cpus, and the cgroup is removed concurrently. The commit 3a5a6d0c2b03 ("cpuset: don't nest cgroup_mutex inside get_online_cpus()") made cpuset_hotplug_workfn asynchronous, This change involves calling flush_work(), which can create a multiple processes circular locking dependency that involve cgroup_mutex, potentially leading to a deadlock. To avoid deadlock. the commit 76bb5ab8f6e3 ("cpuset: break kernfs active protection in cpuset_write_resmask()") added 'kernfs_break_active_protection' in the cpuset_write_resmask. This could lead to this warning. After the commit 2125c0034c5d ("cgroup/cpuset: Make cpuset hotplug processing synchronous"), the cpuset_write_resmask no longer needs to wait the hotplug to finish, which means that concurrent hotplug and cpuset operations are no longer possible. Therefore, the deadlock doesn't exist anymore and it does not have to 'break active protection' now. To fix this warning, just remove kernfs_break_active_protection operation in the 'cpuset_write_resmask'. Fixes: bdb2fd7fc56e ("kernfs: Skip kernfs_drain_open_files() more aggressively") Fixes: 76bb5ab8f6e3 ("cpuset: break kernfs active protection in cpuset_write_resmask()") Reported-by: Ji Fa <jifa@huawei.com> Signed-off-by: Chen Ridong <chenridong@huawei.com> Acked-by: Waiman Long <longman@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2025-01-08sched_ext: switch class when preempted by higher priority schedulerHonglei Wang
ops.cpu_release() function, if defined, must be invoked when preempted by a higher priority scheduler class task. This scenario was skipped in commit f422316d7466 ("sched_ext: Remove switch_class_scx()"). Let's fix it. Fixes: f422316d7466 ("sched_ext: Remove switch_class_scx()") Signed-off-by: Honglei Wang <jameshongleiwang@126.com> Acked-by: Andrea Righi <arighi@nvidia.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2025-01-08sched_ext: Replace rq_lock() to raw_spin_rq_lock() in scx_ops_bypass()Changwoo Min
scx_ops_bypass() iterates all CPUs to re-enqueue all the scx tasks. For each CPU, it acquires a lock using rq_lock() regardless of whether a CPU is offline or the CPU is currently running a task in a higher scheduler class (e.g., deadline). The rq_lock() is supposed to be used for online CPUs, and the use of rq_lock() may trigger an unnecessary warning in rq_pin_lock(). Therefore, replace rq_lock() to raw_spin_rq_lock() in scx_ops_bypass(). Without this change, we observe the following warning: ===== START ===== [ 6.615205] rq->balance_callback && rq->balance_callback != &balance_push_callback [ 6.615208] WARNING: CPU: 2 PID: 0 at kernel/sched/sched.h:1730 __schedule+0x1130/0x1c90 ===== END ===== Fixes: 0e7ffff1b811 ("scx: Fix raciness in scx_ops_bypass()") Signed-off-by: Changwoo Min <changwoo@igalia.com> Acked-by: Andrea Righi <arighi@nvidia.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2025-01-08sched_ext: keep running prev when prev->scx.slice != 0Henry Huang
When %SCX_OPS_ENQ_LAST is set and prev->scx.slice != 0, @prev will be dispacthed into the local DSQ in put_prev_task_scx(). However, pick_task_scx() is executed before put_prev_task_scx(), so it will not pick @prev. Set %SCX_RQ_BAL_KEEP in balance_one() to ensure that pick_task_scx() can pick @prev. Signed-off-by: Henry Huang <henry.hj@antgroup.com> Acked-by: Andrea Righi <arighi@nvidia.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2025-01-06Merge tag 'vfs-6.13-rc7.fixes' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs Pull vfs fixes from Christian Brauner: - Relax assertions on failure to encode file handles The ->encode_fh() method can fail for various reasons. None of them warrant a WARN_ON(). - Fix overlayfs file handle encoding by allowing encoding an fid from an inode without an alias - Make sure fuse_dir_open() handles FOPEN_KEEP_CACHE. If it's not specified fuse needs to invaludate the directory inode page cache - Fix qnx6 so it builds with gcc-15 - Various fixes for netfslib and ceph and nfs filesystems: - Ignore silly rename files from afs and nfs when building header archives - Fix read result collection in netfslib with multiple subrequests - Handle ENOMEM for netfslib buffered reads - Fix oops in nfs_netfs_init_request() - Parse the secctx command immediately in cachefiles - Remove a redundant smp_rmb() in netfslib - Handle recursion in read retry in netfslib - Fix clearing of folio_queue - Fix missing cancellation of copy-to_cache when the cache for a file is temporarly disabled in netfslib - Sanity check the hfs root record - Fix zero padding data issues in concurrent write scenarios - Fix is_mnt_ns_file() after converting nsfs to path_from_stashed() - Fix missing declaration of init_files - Increase I/O priority when writing revoke records in jbd2 - Flush filesystem device before updating tail sequence in jbd2 * tag 'vfs-6.13-rc7.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (23 commits) ovl: support encoding fid from inode with no alias ovl: pass realinode to ovl_encode_real_fh() instead of realdentry fuse: respect FOPEN_KEEP_CACHE on opendir netfs: Fix is-caching check in read-retry netfs: Fix the (non-)cancellation of copy when cache is temporarily disabled netfs: Fix ceph copy to cache on write-begin netfs: Work around recursion by abandoning retry if nothing read netfs: Fix missing barriers by using clear_and_wake_up_bit() netfs: Remove redundant use of smp_rmb() cachefiles: Parse the "secctx" immediately nfs: Fix oops in nfs_netfs_init_request() when copying to cache netfs: Fix enomem handling in buffered reads netfs: Fix non-contiguous donation between completed reads kheaders: Ignore silly-rename files fs: relax assertions on failure to encode file handles fs: fix missing declaration of init_files fs: fix is_mnt_ns_file() iomap: fix zero padding data issue in concurrent append writes iomap: pass byte granular end position to iomap_add_to_ioend jbd2: flush filesystem device before updating tail sequence ...
2025-01-06kernel/cgroup: Add "dmem" memory accounting cgroupMaarten Lankhorst
This code is based on the RDMA and misc cgroup initially, but now uses page_counter. It uses the same min/low/max semantics as the memory cgroup as a result. There's a small mismatch as TTM uses u64, and page_counter long pages. In practice it's not a problem. 32-bits systems don't really come with >=4GB cards and as long as we're consistently wrong with units, it's fine. The device page size may not be in the same units as kernel page size, and each region might also have a different page size (VRAM vs GART for example). The interface is simple: - Call dmem_cgroup_register_region() - Use dmem_cgroup_try_charge to check if you can allocate a chunk of memory, use dmem_cgroup__uncharge when freeing it. This may return an error code, or -EAGAIN when the cgroup limit is reached. In that case a reference to the limiting pool is returned. - The limiting cs can be used as compare function for dmem_cgroup_state_evict_valuable. - After having evicted enough, drop reference to limiting cs with dmem_cgroup_pool_state_put. This API allows you to limit device resources with cgroups. You can see the supported cards in /sys/fs/cgroup/dmem.capacity You need to echo +dmem to cgroup.subtree_control, and then you can partition device memory. Co-developed-by: Friedrich Vock <friedrich.vock@gmx.de> Signed-off-by: Friedrich Vock <friedrich.vock@gmx.de> Co-developed-by: Maxime Ripard <mripard@kernel.org> Signed-off-by: Maarten Lankhorst <dev@lankhorst.se> Acked-by: Tejun Heo <tj@kernel.org> Link: https://lore.kernel.org/r/20241204143112.1250983-1-dev@lankhorst.se Signed-off-by: Maxime Ripard <mripard@kernel.org>
2025-01-05Merge tag 'mm-hotfixes-stable-2025-01-04-18-02' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull hotfixes from Andrew Morton: "25 hotfixes. 16 are cc:stable. 18 are MM and 7 are non-MM. The usual bunch of singletons and two doubletons - please see the relevant changelogs for details" * tag 'mm-hotfixes-stable-2025-01-04-18-02' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (25 commits) MAINTAINERS: change Arınç _NAL's name and email address scripts/sorttable: fix orc_sort_cmp() to maintain symmetry and transitivity mm/util: make memdup_user_nul() similar to memdup_user() mm, madvise: fix potential workingset node list_lru leaks mm/damon/core: fix ignored quota goals and filters of newly committed schemes mm/damon/core: fix new damon_target objects leaks on damon_commit_targets() mm/list_lru: fix false warning of negative counter vmstat: disable vmstat_work on vmstat_cpu_down_prep() mm: shmem: fix the update of 'shmem_falloc->nr_unswapped' mm: shmem: fix incorrect index alignment for within_size policy percpu: remove intermediate variable in PERCPU_PTR() mm: zswap: fix race between [de]compression and CPU hotunplug ocfs2: fix slab-use-after-free due to dangling pointer dqi_priv fs/proc/task_mmu: fix pagemap flags with PMD THP entries on 32bit kcov: mark in_softirq_really() as __always_inline docs: mm: fix the incorrect 'FileHugeMapped' field mailmap: modify the entry for Mathieu Othacehe mm/kmemleak: fix sleeping function called from invalid context at print message mm: hugetlb: independent PMD page table shared count maple_tree: reload mas before the second call for mas_empty_area ...
2025-01-03Merge tag 'sched_ext-for-6.13-rc5-fixes' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext Pull sched_ext fixes from Tejun Heo: - Fix a bug where bpf_iter_scx_dsq_new() was not initializing the iterator's flags and could inadvertently enable e.g. reverse iteration - Fix a bug where scx_ops_bypass() could call irq_restore twice - Add Andrea and Changwoo as maintainers for better review coverage - selftests and tools/sched_ext build and other fixes * tag 'sched_ext-for-6.13-rc5-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext: sched_ext: Fix dsq_local_on selftest sched_ext: initialize kit->cursor.flags sched_ext: Fix invalid irq restore in scx_ops_bypass() MAINTAINERS: add me as reviewer for sched_ext MAINTAINERS: add self as reviewer for sched_ext scx: Fix maximal BPF selftest prog sched_ext: fix application of sizeof to pointer selftests/sched_ext: fix build after renames in sched_ext API sched_ext: Add __weak to fix the build errors
2025-01-03Merge tag 'wq-for-6.13-rc5-fixes' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq Pull workqueue fixes from Tejun Heo: - Suppress a corner case spurious flush dependency warning - Two trivial changes * tag 'wq-for-6.13-rc5-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: workqueue: add printf attribute to __alloc_workqueue() workqueue: Do not warn when cancelling WQ_MEM_RECLAIM work from !WQ_MEM_RECLAIM worker rust: add safety comment in workqueue traits
2025-01-03Merge tag 'ftrace-v6.13-rc5-2' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull ftrace fixes from Steven Rostedt: - Add needed READ_ONCE() around access to the fgraph array element The updates to the fgraph array can happen when callbacks are registered and unregistered. The __ftrace_return_to_handler() can handle reading either the old value or the new value. But once it reads that value it must stay consistent otherwise the check that looks to see if the value is a stub may show false, but if the compiler decides to re-read after that check, it can be true which can cause the code to crash later on. - Make function profiler use the top level ops for filtering again When function graph became available for instances, its filter ops became independent from the top level set_ftrace_filter. In the process the function profiler received its own filter ops as well. But the function profiler uses the top level set_ftrace_filter file and does not have one of its own. In giving it its own filter ops, it lost any user interface it once had. Make it use the top level set_ftrace_filter file again. This fixes a regression. * tag 'ftrace-v6.13-rc5-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ftrace: Fix function profiler's filtering functionality fgraph: Add READ_ONCE() when accessing fgraph_array[]
2025-01-02ftrace: Fix function profiler's filtering functionalityKohei Enju
Commit c132be2c4fcc ("function_graph: Have the instances use their own ftrace_ops for filtering"), function profiler (enabled via function_profile_enabled) has been showing statistics for all functions, ignoring set_ftrace_filter settings. While tracers are instantiated, the function profiler is not. Therefore, it should use the global set_ftrace_filter for consistency. This patch modifies the function profiler to use the global filter, fixing the filtering functionality. Before (filtering not working): ``` root@localhost:~# echo 'vfs*' > /sys/kernel/tracing/set_ftrace_filter root@localhost:~# echo 1 > /sys/kernel/tracing/function_profile_enabled root@localhost:~# sleep 1 root@localhost:~# echo 0 > /sys/kernel/tracing/function_profile_enabled root@localhost:~# head /sys/kernel/tracing/trace_stat/* Function Hit Time Avg s^2 -------- --- ---- --- --- schedule 314 22290594 us 70989.15 us 40372231 us x64_sys_call 1527 8762510 us 5738.382 us 3414354 us schedule_hrtimeout_range 176 8665356 us 49234.98 us 405618876 us __x64_sys_ppoll 324 5656635 us 17458.75 us 19203976 us do_sys_poll 324 5653747 us 17449.83 us 19214945 us schedule_timeout 67 5531396 us 82558.15 us 2136740827 us __x64_sys_pselect6 12 3029540 us 252461.7 us 63296940171 us do_pselect.constprop.0 12 3029532 us 252461.0 us 63296952931 us ``` After (filtering working): ``` root@localhost:~# echo 'vfs*' > /sys/kernel/tracing/set_ftrace_filter root@localhost:~# echo 1 > /sys/kernel/tracing/function_profile_enabled root@localhost:~# sleep 1 root@localhost:~# echo 0 > /sys/kernel/tracing/function_profile_enabled root@localhost:~# head /sys/kernel/tracing/trace_stat/* Function Hit Time Avg s^2 -------- --- ---- --- --- vfs_write 462 68476.43 us 148.217 us 25874.48 us vfs_read 641 9611.356 us 14.994 us 28868.07 us vfs_fstat 890 878.094 us 0.986 us 1.667 us vfs_fstatat 227 757.176 us 3.335 us 18.928 us vfs_statx 226 610.610 us 2.701 us 17.749 us vfs_getattr_nosec 1187 460.919 us 0.388 us 0.326 us vfs_statx_path 297 343.287 us 1.155 us 11.116 us vfs_rename 6 291.575 us 48.595 us 9889.236 us ``` Cc: stable@vger.kernel.org Link: https://lore.kernel.org/20250101190820.72534-1-enjuk@amazon.com Fixes: c132be2c4fcc ("function_graph: Have the instances use their own ftrace_ops for filtering") Signed-off-by: Kohei Enju <enjuk@amazon.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-01-02fgraph: Add READ_ONCE() when accessing fgraph_array[]Zilin Guan
In __ftrace_return_to_handler(), a loop iterates over the fgraph_array[] elements, which are fgraph_ops. The loop checks if an element is a fgraph_stub to prevent using a fgraph_stub afterward. However, if the compiler reloads fgraph_array[] after this check, it might race with an update to fgraph_array[] that introduces a fgraph_stub. This could result in the stub being processed, but the stub contains a null "func_hash" field, leading to a NULL pointer dereference. To ensure that the gops compared against the fgraph_stub matches the gops processed later, add a READ_ONCE(). A similar patch appears in commit 63a8dfb ("function_graph: Add READ_ONCE() when accessing fgraph_array[]"). Cc: stable@vger.kernel.org Fixes: 37238abe3cb47 ("ftrace/function_graph: Pass fgraph_ops to function graph callbacks") Link: https://lore.kernel.org/20241231113731.277668-1-zilin@seu.edu.cn Signed-off-by: Zilin Guan <zilin@seu.edu.cn> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2024-12-31tracing: Have process_string() also allow arraysSteven Rostedt
In order to catch a common bug where a TRACE_EVENT() TP_fast_assign() assigns an address of an allocated string to the ring buffer and then references it in TP_printk(), which can be executed hours later when the string is free, the function test_event_printk() runs on all events as they are registered to make sure there's no unwanted dereferencing. It calls process_string() to handle cases in TP_printk() format that has "%s". It returns whether or not the string is safe. But it can have some false positives. For instance, xe_bo_move() has: TP_printk("move_lacks_source:%s, migrate object %p [size %zu] from %s to %s device_id:%s", __entry->move_lacks_source ? "yes" : "no", __entry->bo, __entry->size, xe_mem_type_to_name[__entry->old_placement], xe_mem_type_to_name[__entry->new_placement], __get_str(device_id)) Where the "%s" references into xe_mem_type_to_name[]. This is an array of pointers that should be safe for the event to access. Instead of flagging this as a bad reference, if a reference points to an array, where the record field is the index, consider it safe. Link: https://lore.kernel.org/all/9dee19b6185d325d0e6fa5f7cbba81d007d99166.camel@sapience.com/ Cc: stable@vger.kernel.org Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Link: https://lore.kernel.org/20241231000646.324fb5f7@gandalf.local.home Fixes: 65a25d9f7ac02 ("tracing: Add "%s" check in test_event_printk()") Reported-by: Genes Lists <lists@sapience.com> Tested-by: Gene C <arch@sapience.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2024-12-30kcov: mark in_softirq_really() as __always_inlineArnd Bergmann
If gcc decides not to inline in_softirq_really(), objtool warns about a function call with UACCESS enabled: kernel/kcov.o: warning: objtool: __sanitizer_cov_trace_pc+0x1e: call to in_softirq_really() with UACCESS enabled kernel/kcov.o: warning: objtool: check_kcov_mode+0x11: call to in_softirq_really() with UACCESS enabled Mark this as __always_inline to avoid the problem. Link: https://lkml.kernel.org/r/20241217071814.2261620-1-arnd@kernel.org Fixes: 7d4df2dad312 ("kcov: properly check for softirq context") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Marco Elver <elver@google.com> Cc: Aleksandr Nogikh <nogikh@google.com> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Josh Poimboeuf <jpoimboe@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-12-29Merge tag 'locking-urgent-2024-12-29' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking fix from Ingo Molnar: "Fix missed rtmutex wakeups causing sporadic boot hangs and other misbehavior" * tag 'locking-urgent-2024-12-29' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/rtmutex: Make sure we wake anything on the wake_q when we release the lock->wait_lock
2024-12-27Merge tag 'probes-fixes-v6.13-rc4' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull probes fix from Masami Hiramatsu: "Change the priority of the module callback of kprobe events so that it is called after the jump label list on the module is updated. This ensures the kprobe can check whether it is not on the jump label address correctly" * tag 'probes-fixes-v6.13-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: tracing/kprobe: Make trace_kprobe's module callback called after jump_label update
2024-12-24sched_ext: initialize kit->cursor.flagsHenry Huang
struct bpf_iter_scx_dsq *it maybe not initialized. If we didn't call scx_bpf_dsq_move_set_vtime and scx_bpf_dsq_move_set_slice before scx_bpf_dsq_move, it would cause unexpected behaviors: 1. Assign a huge slice into p->scx.slice 2. Assign a invalid vtime into p->scx.dsq_vtime Signed-off-by: Henry Huang <henry.hj@antgroup.com> Fixes: 6462dd53a260 ("sched_ext: Compact struct bpf_iter_scx_dsq_kern") Cc: stable@vger.kernel.org # v6.12 Signed-off-by: Tejun Heo <tj@kernel.org>
2024-12-24workqueue: add printf attribute to __alloc_workqueue()Su Hui
Fix a compiler warning with W=1: kernel/workqueue.c: error: function ‘__alloc_workqueue’ might be a candidate for ‘gnu_printf’ format attribute[-Werror=suggest-attribute=format] 5657 | name_len = vsnprintf(wq->name, sizeof(wq->name), fmt, args); | ^~~~~~~~ Fixes: 9b59a85a84dc ("workqueue: Don't call va_start / va_end twice") Signed-off-by: Su Hui <suhui@nfschina.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2024-12-23tracing: Prevent bad count for tracing_cpumask_writeLizhi Xu
If a large count is provided, it will trigger a warning in bitmap_parse_user. Also check zero for it. Cc: stable@vger.kernel.org Fixes: 9e01c1b74c953 ("cpumask: convert kernel trace functions") Link: https://lore.kernel.org/20241216073238.2573704-1-lizhi.xu@windriver.com Reported-by: syzbot+0aecfd34fb878546f3fd@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=0aecfd34fb878546f3fd Tested-by: syzbot+0aecfd34fb878546f3fd@syzkaller.appspotmail.com Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com> Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2024-12-24tracing/kprobe: Make trace_kprobe's module callback called after jump_label ↵Masami Hiramatsu (Google)
update Make sure the trace_kprobe's module notifer callback function is called after jump_label's callback is called. Since the trace_kprobe's callback eventually checks jump_label address during registering new kprobe on the loading module, jump_label must be updated before this registration happens. Link: https://lore.kernel.org/all/173387585556.995044.3157941002975446119.stgit@devnote2/ Fixes: 614243181050 ("tracing/kprobes: Support module init function probing") Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
2024-12-21Merge tag 'mm-hotfixes-stable-2024-12-21-12-09' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Pull misc fixes from Andrew Morton: "25 hotfixes. 16 are cc:stable. 19 are MM and 6 are non-MM. The usual bunch of singletons and doubletons - please see the relevant changelogs for details" * tag 'mm-hotfixes-stable-2024-12-21-12-09' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (25 commits) mm: huge_memory: handle strsep not finding delimiter alloc_tag: fix set_codetag_empty() when !CONFIG_MEM_ALLOC_PROFILING_DEBUG alloc_tag: fix module allocation tags populated area calculation mm/codetag: clear tags before swap mm/vmstat: fix a W=1 clang compiler warning mm: convert partially_mapped set/clear operations to be atomic nilfs2: fix buffer head leaks in calls to truncate_inode_pages() vmalloc: fix accounting with i915 mm/page_alloc: don't call pfn_to_page() on possibly non-existent PFN in split_large_buddy() fork: avoid inappropriate uprobe access to invalid mm nilfs2: prevent use of deleted inode zram: fix uninitialized ZRAM not releasing backing device zram: refuse to use zero sized block device as backing device mm: use clear_user_(high)page() for arch with special user folio handling mm: introduce cpu_icache_is_aliasing() across all architectures mm: add RCU annotation to pte_offset_map(_lock) mm: correctly reference merged VMA mm: use aligned address in copy_user_gigantic_page() mm: use aligned address in clear_gigantic_page() mm: shmem: fix ShmemHugePages at swapout ...
2024-12-21Merge tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpfLinus Torvalds
Pull BPF fixes from Daniel Borkmann: - Fix inlining of bpf_get_smp_processor_id helper for !CONFIG_SMP systems (Andrea Righi) - Fix BPF USDT selftests helper code to use asm constraint "m" for LoongArch (Tiezhu Yang) - Fix BPF selftest compilation error in get_uprobe_offset when PROCMAP_QUERY is not defined (Jerome Marchand) - Fix BPF bpf_skb_change_tail helper when used in context of BPF sockmap to handle negative skb header offsets (Cong Wang) - Several fixes to BPF sockmap code, among others, in the area of socket buffer accounting (Levi Zim, Zijian Zhang, Cong Wang) * tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf: selftests/bpf: Test bpf_skb_change_tail() in TC ingress selftests/bpf: Introduce socket_helpers.h for TC tests selftests/bpf: Add a BPF selftest for bpf_skb_change_tail() bpf: Check negative offsets in __bpf_skb_min_len() tcp_bpf: Fix copied value in tcp_bpf_sendmsg skmsg: Return copied bytes in sk_msg_memcopy_from_iter tcp_bpf: Add sk_rmem_alloc related logic for tcp_bpf ingress redirection tcp_bpf: Charge receive socket buffer in bpf_tcp_ingress() selftests/bpf: Fix compilation error in get_uprobe_offset() selftests/bpf: Use asm constraint "m" for LoongArch bpf: Fix bpf_get_smp_processor_id() on !CONFIG_SMP
2024-12-20kheaders: Ignore silly-rename filesDavid Howells
Tell tar to ignore silly-rename files (".__afs*" and ".nfs*") when building the header archive. These occur when a file that is open is unlinked locally, but hasn't yet been closed. Such files are visible to the user via the getdents() syscall and so programs may want to do things with them. During the kernel build, such files may be made during the processing of header files and the cleanup may get deferred by fput() which may result in tar seeing these files when it reads the directory, but they may have disappeared by the time it tries to open them, causing tar to fail with an error. Further, we don't want to include them in the tarball if they still exist. With CONFIG_HEADERS_INSTALL=y, something like the following may be seen: find: './kernel/.tmp_cpio_dir/include/dt-bindings/reset/.__afs2080': No such file or directory tar: ./include/linux/greybus/.__afs3C95: File removed before we read it The find warning doesn't seem to cause a problem. Fix this by telling tar when called from in gen_kheaders.sh to exclude such files. This only affects afs and nfs; cifs uses the Windows Hidden attribute to prevent the file from being seen. Signed-off-by: David Howells <dhowells@redhat.com> Link: https://lore.kernel.org/r/20241213135013.2964079-2-dhowells@redhat.com cc: Masahiro Yamada <masahiroy@kernel.org> cc: Marc Dionne <marc.dionne@auristor.com> cc: linux-afs@lists.infradead.org cc: linux-nfs@vger.kernel.org cc: linux-kernel@vger.kernel.org Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-12-20Merge tag 'trace-ringbuffer-v6.13-rc3' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull ring-buffer fixes from Steven Rostedt: - Fix possible overflow of mmapped ring buffer with bad offset If the mmap() to the ring buffer passes in a start address that is passed the end of the mmapped file, it is not caught and a slab-out-of-bounds is triggered. Add a check to make sure the start address is within the bounds - Do not use TP_printk() to boot mapped ring buffers As a boot mapped ring buffer's data may have pointers that map to the previous boot's memory map, it is unsafe to allow the TP_printk() to be used to read the boot mapped buffer's events. If a TP_printk() points to a static string from within the kernel it will not match the current kernel mapping if KASLR is active, and it can fault. Have it simply print out the raw fields. * tag 'trace-ringbuffer-v6.13-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: trace/ring-buffer: Do not use TP_printk() formatting for boot mapped buffers ring-buffer: Fix overflow in __rb_map_vma
2024-12-19workqueue: Do not warn when cancelling WQ_MEM_RECLAIM work from ↵Tvrtko Ursulin
!WQ_MEM_RECLAIM worker After commit 746ae46c1113 ("drm/sched: Mark scheduler work queues with WQ_MEM_RECLAIM") amdgpu started seeing the following warning: [ ] workqueue: WQ_MEM_RECLAIM sdma0:drm_sched_run_job_work [gpu_sched] is flushing !WQ_MEM_RECLAIM events:amdgpu_device_delay_enable_gfx_off [amdgpu] ... [ ] Workqueue: sdma0 drm_sched_run_job_work [gpu_sched] ... [ ] Call Trace: [ ] <TASK> ... [ ] ? check_flush_dependency+0xf5/0x110 ... [ ] cancel_delayed_work_sync+0x6e/0x80 [ ] amdgpu_gfx_off_ctrl+0xab/0x140 [amdgpu] [ ] amdgpu_ring_alloc+0x40/0x50 [amdgpu] [ ] amdgpu_ib_schedule+0xf4/0x810 [amdgpu] [ ] ? drm_sched_run_job_work+0x22c/0x430 [gpu_sched] [ ] amdgpu_job_run+0xaa/0x1f0 [amdgpu] [ ] drm_sched_run_job_work+0x257/0x430 [gpu_sched] [ ] process_one_work+0x217/0x720 ... [ ] </TASK> The intent of the verifcation done in check_flush_depedency is to ensure forward progress during memory reclaim, by flagging cases when either a memory reclaim process, or a memory reclaim work item is flushed from a context not marked as memory reclaim safe. This is correct when flushing, but when called from the cancel(_delayed)_work_sync() paths it is a false positive because work is either already running, or will not be running at all. Therefore cancelling it is safe and we can relax the warning criteria by letting the helper know of the calling context. Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com> Fixes: fca839c00a12 ("workqueue: warn if memory reclaim tries to flush !WQ_MEM_RECLAIM workqueue") References: 746ae46c1113 ("drm/sched: Mark scheduler work queues with WQ_MEM_RECLAIM") Cc: Tejun Heo <tj@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Alex Deucher <alexander.deucher@amd.com> Cc: Christian König <christian.koenig@amd.com Cc: Matthew Brost <matthew.brost@intel.com> Cc: <stable@vger.kernel.org> # v4.5+ Signed-off-by: Tejun Heo <tj@kernel.org>
2024-12-18fork: avoid inappropriate uprobe access to invalid mmLorenzo Stoakes
If dup_mmap() encounters an issue, currently uprobe is able to access the relevant mm via the reverse mapping (in build_map_info()), and if we are very unlucky with a race window, observe invalid XA_ZERO_ENTRY state which we establish as part of the fork error path. This occurs because uprobe_write_opcode() invokes anon_vma_prepare() which in turn invokes find_mergeable_anon_vma() that uses a VMA iterator, invoking vma_iter_load() which uses the advanced maple tree API and thus is able to observe XA_ZERO_ENTRY entries added to dup_mmap() in commit d24062914837 ("fork: use __mt_dup() to duplicate maple tree in dup_mmap()"). This change was made on the assumption that only process tear-down code would actually observe (and make use of) these values. However this very unlikely but still possible edge case with uprobes exists and unfortunately does make these observable. The uprobe operation prevents races against the dup_mmap() operation via the dup_mmap_sem semaphore, which is acquired via uprobe_start_dup_mmap() and dropped via uprobe_end_dup_mmap(), and held across register_for_each_vma() prior to invoking build_map_info() which does the reverse mapping lookup. Currently these are acquired and dropped within dup_mmap(), which exposes the race window prior to error handling in the invoking dup_mm() which tears down the mm. We can avoid all this by just moving the invocation of uprobe_start_dup_mmap() and uprobe_end_dup_mmap() up a level to dup_mm() and only release this lock once the dup_mmap() operation succeeds or clean up is done. This means that the uprobe code can never observe an incompletely constructed mm and resolves the issue in this case. Link: https://lkml.kernel.org/r/20241210172412.52995-1-lorenzo.stoakes@oracle.com Fixes: d24062914837 ("fork: use __mt_dup() to duplicate maple tree in dup_mmap()") Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Reported-by: syzbot+2d788f4f7cb660dac4b7@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/6756d273.050a0220.2477f.003d.GAE@google.com/ Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Arnaldo Carvalho de Melo <acme@kernel.org> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Kan Liang <kan.liang@linux.intel.com> Cc: Liam R. Howlett <Liam.Howlett@Oracle.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peng Zhang <zhangpeng.00@bytedance.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: David Hildenbrand <david@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
generated by cgit (git 2.34.1) at 2025-05-10 02:37:23 +0000