From 6f86bdeab633a56d5c6dccf1a2c5989b6a5e323e Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Thu, 27 Feb 2025 16:39:44 -0500 Subject: [PATCH 01/16] tracing: Fix bad hist from corrupting named_triggers list The following commands causes a crash: ~# cd /sys/kernel/tracing/events/rcu/rcu_callback ~# echo 'hist:name=bad:keys=common_pid:onmax(bogus).save(common_pid)' > trigger bash: echo: write error: Invalid argument ~# echo 'hist:name=bad:keys=common_pid' > trigger Because the following occurs: event_trigger_write() { trigger_process_regex() { event_hist_trigger_parse() { data = event_trigger_alloc(..); event_trigger_register(.., data) { cmd_ops->reg(.., data, ..) [hist_register_trigger()] { data->ops->init() [event_hist_trigger_init()] { save_named_trigger(name, data) { list_add(&data->named_list, &named_triggers); } } } } ret = create_actions(); (return -EINVAL) if (ret) goto out_unreg; [..] ret = hist_trigger_enable(data, ...) { list_add_tail_rcu(&data->list, &file->triggers); <<<---- SKIPPED!!! (this is important!) [..] out_unreg: event_hist_unregister(.., data) { cmd_ops->unreg(.., data, ..) [hist_unregister_trigger()] { list_for_each_entry(iter, &file->triggers, list) { if (!hist_trigger_match(data, iter, named_data, false)) <- never matches continue; [..] test = iter; } if (test && test->ops->free) <<<-- test is NULL test->ops->free(test) [event_hist_trigger_free()] { [..] if (data->name) del_named_trigger(data) { list_del(&data->named_list); <<<<-- NEVER gets removed! } } } } [..] kfree(data); <<<-- frees item but it is still on list The next time a hist with name is registered, it causes an u-a-f bug and the kernel can crash. Move the code around such that if event_trigger_register() succeeds, the next thing called is hist_trigger_enable() which adds it to the list. A bunch of actions is called if get_named_trigger_data() returns false. But that doesn't need to be called after event_trigger_register(), so it can be moved up, allowing event_trigger_register() to be called just before hist_trigger_enable() keeping them together and allowing the file->triggers to be properly populated. Cc: stable@vger.kernel.org Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Link: https://lore.kernel.org/20250227163944.1c37f85f@gandalf.local.home Fixes: 067fe038e70f6 ("tracing: Add variable reference handling to hist triggers") Reported-by: Tomas Glozar Tested-by: Tomas Glozar Reviewed-by: Tom Zanussi Closes: https://lore.kernel.org/all/CAP4=nvTsxjckSBTz=Oe_UYh8keD9_sZC4i++4h72mJLic4_W4A@mail.gmail.com/ Signed-off-by: Steven Rostedt (Google) --- kernel/trace/trace_events_hist.c | 30 +++++++++++++++--------------- 1 file changed, 15 insertions(+), 15 deletions(-) diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c index 261163b00137..ad7419e24055 100644 --- a/kernel/trace/trace_events_hist.c +++ b/kernel/trace/trace_events_hist.c @@ -6724,27 +6724,27 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops, if (existing_hist_update_only(glob, trigger_data, file)) goto out_free; - ret = event_trigger_register(cmd_ops, file, glob, trigger_data); - if (ret < 0) - goto out_free; + if (!get_named_trigger_data(trigger_data)) { - if (get_named_trigger_data(trigger_data)) - goto enable; + ret = create_actions(hist_data); + if (ret) + goto out_free; - ret = create_actions(hist_data); - if (ret) - goto out_unreg; + if (has_hist_vars(hist_data) || hist_data->n_var_refs) { + ret = save_hist_vars(hist_data); + if (ret) + goto out_free; + } - if (has_hist_vars(hist_data) || hist_data->n_var_refs) { - ret = save_hist_vars(hist_data); + ret = tracing_map_init(hist_data->map); if (ret) - goto out_unreg; + goto out_free; } - ret = tracing_map_init(hist_data->map); - if (ret) - goto out_unreg; -enable: + ret = event_trigger_register(cmd_ops, file, glob, trigger_data); + if (ret < 0) + goto out_free; + ret = hist_trigger_enable(trigger_data, file); if (ret) goto out_unreg; -- 2.50.1 From 3908b6baf2ac20138915b5ca98338b4f063954d8 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Wed, 26 Feb 2025 15:27:03 +0100 Subject: [PATCH 02/16] selftests/ftrace: Let fprobe test consider already enabled functions The fprobe test fails on Fedora 41 since the fprobe test assumption that the number of enabled_functions is zero before the test starts is not necessarily true. Some user space tools, like systemd, add BPF programs that attach to functions. Those will show up in the enabled_functions table and must be taken into account by the fprobe test. Therefore count the number of lines of enabled_functions before tests start, and use that as base when comparing expected results. Cc: Mark Rutland Cc: Mathieu Desnoyers Cc: Andrew Morton Cc: Sven Schnelle Cc: Vasily Gorbik Cc: Alexander Gordeev Link: https://lore.kernel.org/20250226142703.910860-1-hca@linux.ibm.com Fixes: e85c5e9792b9 ("selftests/ftrace: Update fprobe test to check enabled_functions file") Signed-off-by: Heiko Carstens Acked-by: Masami Hiramatsu (Google) Signed-off-by: Steven Rostedt (Google) --- .../test.d/dynevent/add_remove_fprobe.tc | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe.tc b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe.tc index 449f9d8be746..73f6c6fcecab 100644 --- a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe.tc +++ b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe.tc @@ -10,12 +10,16 @@ PLACE=$FUNCTION_FORK PLACE2="kmem_cache_free" PLACE3="schedule_timeout" +# Some functions may have BPF programs attached, therefore +# count already enabled_functions before tests start +ocnt=`cat enabled_functions | wc -l` + echo "f:myevent1 $PLACE" >> dynamic_events # Make sure the event is attached and is the only one grep -q $PLACE enabled_functions cnt=`cat enabled_functions | wc -l` -if [ $cnt -ne 1 ]; then +if [ $cnt -ne $((ocnt + 1)) ]; then exit_fail fi @@ -23,7 +27,7 @@ echo "f:myevent2 $PLACE%return" >> dynamic_events # It should till be the only attached function cnt=`cat enabled_functions | wc -l` -if [ $cnt -ne 1 ]; then +if [ $cnt -ne $((ocnt + 1)) ]; then exit_fail fi @@ -32,7 +36,7 @@ echo "f:myevent3 $PLACE2" >> dynamic_events grep -q $PLACE2 enabled_functions cnt=`cat enabled_functions | wc -l` -if [ $cnt -ne 2 ]; then +if [ $cnt -ne $((ocnt + 2)) ]; then exit_fail fi @@ -49,7 +53,7 @@ grep -q myevent1 dynamic_events # should still have 2 left cnt=`cat enabled_functions | wc -l` -if [ $cnt -ne 2 ]; then +if [ $cnt -ne $((ocnt + 2)) ]; then exit_fail fi @@ -57,7 +61,7 @@ echo > dynamic_events # Should have none left cnt=`cat enabled_functions | wc -l` -if [ $cnt -ne 0 ]; then +if [ $cnt -ne $ocnt ]; then exit_fail fi @@ -65,7 +69,7 @@ echo "f:myevent4 $PLACE" >> dynamic_events # Should only have one enabled cnt=`cat enabled_functions | wc -l` -if [ $cnt -ne 1 ]; then +if [ $cnt -ne $((ocnt + 1)) ]; then exit_fail fi @@ -73,7 +77,7 @@ echo > dynamic_events # Should have none left cnt=`cat enabled_functions | wc -l` -if [ $cnt -ne 0 ]; then +if [ $cnt -ne $ocnt ]; then exit_fail fi -- 2.50.1 From a1a7eb89ca0b89dc1c326eeee2596f263291aca3 Mon Sep 17 00:00:00 2001 From: Nikolay Kuratov Date: Thu, 6 Feb 2025 12:01:56 +0300 Subject: [PATCH 03/16] ftrace: Avoid potential division by zero in function_stat_show() Check whether denominator expression x * (x - 1) * 1000 mod {2^32, 2^64} produce zero and skip stddev computation in that case. For now don't care about rec->counter * rec->counter overflow because rec->time * rec->time overflow will likely happen earlier. Cc: stable@vger.kernel.org Cc: Wen Yang Cc: Mark Rutland Cc: Mathieu Desnoyers Link: https://lore.kernel.org/20250206090156.1561783-1-kniv@yandex-team.ru Fixes: e31f7939c1c27 ("ftrace: Avoid potential division by zero in function profiler") Signed-off-by: Nikolay Kuratov Signed-off-by: Steven Rostedt (Google) --- kernel/trace/ftrace.c | 27 ++++++++++++--------------- 1 file changed, 12 insertions(+), 15 deletions(-) diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 6b0c25761ccb..fc88e0688daf 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -540,6 +540,7 @@ static int function_stat_show(struct seq_file *m, void *v) static struct trace_seq s; unsigned long long avg; unsigned long long stddev; + unsigned long long stddev_denom; #endif guard(mutex)(&ftrace_profile_lock); @@ -559,23 +560,19 @@ static int function_stat_show(struct seq_file *m, void *v) #ifdef CONFIG_FUNCTION_GRAPH_TRACER seq_puts(m, " "); - /* Sample standard deviation (s^2) */ - if (rec->counter <= 1) - stddev = 0; - else { - /* - * Apply Welford's method: - * s^2 = 1 / (n * (n-1)) * (n * \Sum (x_i)^2 - (\Sum x_i)^2) - */ + /* + * Variance formula: + * s^2 = 1 / (n * (n-1)) * (n * \Sum (x_i)^2 - (\Sum x_i)^2) + * Maybe Welford's method is better here? + * Divide only by 1000 for ns^2 -> us^2 conversion. + * trace_print_graph_duration will divide by 1000 again. + */ + stddev = 0; + stddev_denom = rec->counter * (rec->counter - 1) * 1000; + if (stddev_denom) { stddev = rec->counter * rec->time_squared - rec->time * rec->time; - - /* - * Divide only 1000 for ns^2 -> us^2 conversion. - * trace_print_graph_duration will divide 1000 again. - */ - stddev = div64_ul(stddev, - rec->counter * (rec->counter - 1) * 1000); + stddev = div64_ul(stddev, stddev_denom); } trace_seq_init(&s); -- 2.50.1 From c5b0320bbf79548fbf058a3925a07c8f281beeab Mon Sep 17 00:00:00 2001 From: Alejandro Jimenez Date: Mon, 6 Jan 2025 19:14:13 +0000 Subject: [PATCH 04/16] iommu/amd: Preserve default DTE fields when updating Host Page Table Root When updating the page table root field on the DTE, avoid overwriting any bits that are already set. The earlier call to make_clear_dte() writes default values that all DTEs must have set (currently DTE[V]), and those must be preserved. Currently this doesn't cause problems since the page table root update is the first field that is set after make_clear_dte() is called, and DTE_FLAG_V is set again later along with the permission bits (IR/IW). Remove this redundant assignment too. Fixes: fd5dff9de4be ("iommu/amd: Modify set_dte_entry() to use 256-bit DTE helpers") Signed-off-by: Alejandro Jimenez Reviewed-by: Dheeraj Kumar Srivastava Reviewed-by: Vasant Hegde Link: https://lore.kernel.org/r/20250106191413.3107140-1-alejandro.j.jimenez@oracle.com Signed-off-by: Joerg Roedel --- drivers/iommu/amd/iommu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/iommu/amd/iommu.c b/drivers/iommu/amd/iommu.c index b48a72bd7b23..cd5116d8c3b2 100644 --- a/drivers/iommu/amd/iommu.c +++ b/drivers/iommu/amd/iommu.c @@ -2043,12 +2043,12 @@ static void set_dte_entry(struct amd_iommu *iommu, make_clear_dte(dev_data, dte, &new); if (domain->iop.mode != PAGE_MODE_NONE) - new.data[0] = iommu_virt_to_phys(domain->iop.root); + new.data[0] |= iommu_virt_to_phys(domain->iop.root); new.data[0] |= (domain->iop.mode & DEV_ENTRY_MODE_MASK) << DEV_ENTRY_MODE_SHIFT; - new.data[0] |= DTE_FLAG_IR | DTE_FLAG_IW | DTE_FLAG_V; + new.data[0] |= DTE_FLAG_IR | DTE_FLAG_IW; /* * When SNP is enabled, we can only support TV=1 with non-zero domain ID. -- 2.50.1 From 64f792981e35e191eb619f6f2fefab76cc7d6112 Mon Sep 17 00:00:00 2001 From: Jerry Snitselaar Date: Fri, 28 Feb 2025 18:27:25 +0800 Subject: [PATCH 05/16] iommu/vt-d: Remove device comparison in context_setup_pass_through_cb Remove the device comparison check in context_setup_pass_through_cb. pci_for_each_dma_alias already makes a decision on whether the callback function should be called for a device. With the check in place it will fail to create context entries for aliases as it walks up to the root bus. Fixes: 2031c469f816 ("iommu/vt-d: Add support for static identity domain") Closes: https://lore.kernel.org/linux-iommu/82499eb6-00b7-4f83-879a-e97b4144f576@linux.intel.com/ Cc: stable@vger.kernel.org Signed-off-by: Jerry Snitselaar Link: https://lore.kernel.org/r/20250224180316.140123-1-jsnitsel@redhat.com Signed-off-by: Lu Baolu Signed-off-by: Joerg Roedel --- drivers/iommu/intel/iommu.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index cc46098f875b..4d8d4593c9c8 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -4378,9 +4378,6 @@ static int context_setup_pass_through_cb(struct pci_dev *pdev, u16 alias, void * { struct device *dev = data; - if (dev != &pdev->dev) - return 0; - return context_setup_pass_through(dev, PCI_BUS_NUM(alias), alias & 0xff); } -- 2.50.1 From b150654f74bf0df8e6a7936d5ec51400d9ec06d8 Mon Sep 17 00:00:00 2001 From: Lu Baolu Date: Fri, 28 Feb 2025 18:27:26 +0800 Subject: [PATCH 06/16] iommu/vt-d: Fix suspicious RCU usage Commit ("iommu/vt-d: Allocate DMAR fault interrupts locally") moved the call to enable_drhd_fault_handling() to a code path that does not hold any lock while traversing the drhd list. Fix it by ensuring the dmar_global_lock lock is held when traversing the drhd list. Without this fix, the following warning is triggered: ============================= WARNING: suspicious RCU usage 6.14.0-rc3 #55 Not tainted ----------------------------- drivers/iommu/intel/dmar.c:2046 RCU-list traversed in non-reader section!! other info that might help us debug this: rcu_scheduler_active = 1, debug_locks = 1 2 locks held by cpuhp/1/23: #0: ffffffff84a67c50 (cpu_hotplug_lock){++++}-{0:0}, at: cpuhp_thread_fun+0x87/0x2c0 #1: ffffffff84a6a380 (cpuhp_state-up){+.+.}-{0:0}, at: cpuhp_thread_fun+0x87/0x2c0 stack backtrace: CPU: 1 UID: 0 PID: 23 Comm: cpuhp/1 Not tainted 6.14.0-rc3 #55 Call Trace: dump_stack_lvl+0xb7/0xd0 lockdep_rcu_suspicious+0x159/0x1f0 ? __pfx_enable_drhd_fault_handling+0x10/0x10 enable_drhd_fault_handling+0x151/0x180 cpuhp_invoke_callback+0x1df/0x990 cpuhp_thread_fun+0x1ea/0x2c0 smpboot_thread_fn+0x1f5/0x2e0 ? __pfx_smpboot_thread_fn+0x10/0x10 kthread+0x12a/0x2d0 ? __pfx_kthread+0x10/0x10 ret_from_fork+0x4a/0x60 ? __pfx_kthread+0x10/0x10 ret_from_fork_asm+0x1a/0x30 Holding the lock in enable_drhd_fault_handling() triggers a lockdep splat about a possible deadlock between dmar_global_lock and cpu_hotplug_lock. This is avoided by not holding dmar_global_lock when calling iommu_device_register(), which initiates the device probe process. Fixes: d74169ceb0d2 ("iommu/vt-d: Allocate DMAR fault interrupts locally") Reported-and-tested-by: Ido Schimmel Closes: https://lore.kernel.org/linux-iommu/Zx9OwdLIc_VoQ0-a@shredder.mtl.com/ Tested-by: Breno Leitao Cc: stable@vger.kernel.org Signed-off-by: Lu Baolu Reviewed-by: Kevin Tian Link: https://lore.kernel.org/r/20250218022422.2315082-1-baolu.lu@linux.intel.com Tested-by: Ido Schimmel Signed-off-by: Joerg Roedel --- drivers/iommu/intel/dmar.c | 1 + drivers/iommu/intel/iommu.c | 7 +++++++ 2 files changed, 8 insertions(+) diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c index 9f424acf474e..e540092d664d 100644 --- a/drivers/iommu/intel/dmar.c +++ b/drivers/iommu/intel/dmar.c @@ -2043,6 +2043,7 @@ int enable_drhd_fault_handling(unsigned int cpu) /* * Enable fault control interrupt. */ + guard(rwsem_read)(&dmar_global_lock); for_each_iommu(iommu, drhd) { u32 fault_status; int ret; diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index 4d8d4593c9c8..bf1f0c814348 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -3146,7 +3146,14 @@ int __init intel_iommu_init(void) iommu_device_sysfs_add(&iommu->iommu, NULL, intel_iommu_groups, "%s", iommu->name); + /* + * The iommu device probe is protected by the iommu_probe_device_lock. + * Release the dmar_global_lock before entering the device probe path + * to avoid unnecessary lock order splat. + */ + up_read(&dmar_global_lock); iommu_device_register(&iommu->iommu, &intel_iommu_ops, NULL); + down_read(&dmar_global_lock); iommu_pmu_register(iommu); } -- 2.50.1 From b654f7a51ffb386131de42aa98ed831f8c126546 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Fri, 28 Feb 2025 21:26:56 +0800 Subject: [PATCH 07/16] block: fix 'kmem_cache of name 'bio-108' already exists' Device mapper bioset often has big bio_slab size, which can be more than 1000, then 8byte can't hold the slab name any more, cause the kmem_cache allocation warning of 'kmem_cache of name 'bio-108' already exists'. Fix the warning by extending bio_slab->name to 12 bytes, but fix output of /proc/slabinfo Reported-by: Guangwu Zhang Signed-off-by: Ming Lei Link: https://lore.kernel.org/r/20250228132656.2838008-1-ming.lei@redhat.com Signed-off-by: Jens Axboe --- block/bio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/block/bio.c b/block/bio.c index f0c416e5931d..6ac5983ba51e 100644 --- a/block/bio.c +++ b/block/bio.c @@ -77,7 +77,7 @@ struct bio_slab { struct kmem_cache *slab; unsigned int slab_ref; unsigned int slab_size; - char name[8]; + char name[12]; }; static DEFINE_MUTEX(bio_slab_lock); static DEFINE_XARRAY(bio_slabs); -- 2.50.1 From 64407f4b5807dc9dec8135e1bfd45d2cb11b4ea0 Mon Sep 17 00:00:00 2001 From: Dan Carpenter Date: Fri, 28 Feb 2025 16:03:47 +0300 Subject: [PATCH 08/16] gpiolib: Fix Oops in gpiod_direction_input_nonotify() The gpiod_direction_input_nonotify() function is supposed to return zero if the direction for the pin is input. But instead it accidentally returns GPIO_LINE_DIRECTION_IN (1) which will be cast into an ERR_PTR() in gpiochip_request_own_desc(). The callers dereference it and it leads to a crash. I changed gpiod_direction_output_raw_commit() just for consistency but returning GPIO_LINE_DIRECTION_OUT (0) is fine. Cc: stable@vger.kernel.org Fixes: 9d846b1aebbe ("gpiolib: check the return value of gpio_chip::get_direction()") Signed-off-by: Dan Carpenter Link: https://lore.kernel.org/r/254f3925-3015-4c9d-aac5-bb9b4b2cd2c5@stanley.mountain [Bartosz: moved the variable declarations to the top of the functions] Signed-off-by: Bartosz Golaszewski --- drivers/gpio/gpiolib.c | 20 ++++++++++---------- 1 file changed, 10 insertions(+), 10 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index fc19df5a64c2..8741600af7ef 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -2712,7 +2712,7 @@ EXPORT_SYMBOL_GPL(gpiod_direction_input); int gpiod_direction_input_nonotify(struct gpio_desc *desc) { - int ret = 0; + int ret = 0, dir; CLASS(gpio_chip_guard, guard)(desc); if (!guard.gc) @@ -2740,12 +2740,12 @@ int gpiod_direction_input_nonotify(struct gpio_desc *desc) ret = guard.gc->direction_input(guard.gc, gpio_chip_hwgpio(desc)); } else if (guard.gc->get_direction) { - ret = guard.gc->get_direction(guard.gc, + dir = guard.gc->get_direction(guard.gc, gpio_chip_hwgpio(desc)); - if (ret < 0) - return ret; + if (dir < 0) + return dir; - if (ret != GPIO_LINE_DIRECTION_IN) { + if (dir != GPIO_LINE_DIRECTION_IN) { gpiod_warn(desc, "%s: missing direction_input() operation and line is output\n", __func__); @@ -2764,7 +2764,7 @@ int gpiod_direction_input_nonotify(struct gpio_desc *desc) static int gpiod_direction_output_raw_commit(struct gpio_desc *desc, int value) { - int val = !!value, ret = 0; + int val = !!value, ret = 0, dir; CLASS(gpio_chip_guard, guard)(desc); if (!guard.gc) @@ -2788,12 +2788,12 @@ static int gpiod_direction_output_raw_commit(struct gpio_desc *desc, int value) } else { /* Check that we are in output mode if we can */ if (guard.gc->get_direction) { - ret = guard.gc->get_direction(guard.gc, + dir = guard.gc->get_direction(guard.gc, gpio_chip_hwgpio(desc)); - if (ret < 0) - return ret; + if (dir < 0) + return dir; - if (ret != GPIO_LINE_DIRECTION_OUT) { + if (dir != GPIO_LINE_DIRECTION_OUT) { gpiod_warn(desc, "%s: missing direction_output() operation\n", __func__); -- 2.50.1 From c157d351460bcf202970e97e611cb6b54a3dd4a4 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Tue, 25 Feb 2025 23:37:08 +0100 Subject: [PATCH 09/16] intel_idle: Handle older CPUs, which stop the TSC in deeper C states, correctly The Intel idle driver is preferred over the ACPI processor idle driver, but fails to implement the work around for Core2 generation CPUs, where the TSC stops in C2 and deeper C-states. This causes stalls and boot delays, when the clocksource watchdog does not catch the unstable TSC before the CPU goes deep idle for the first time. The ACPI driver marks the TSC unstable when it detects that the CPU supports C2 or deeper and the CPU does not have a non-stop TSC. Add the equivivalent work around to the Intel idle driver to cure that. Fixes: 18734958e9bf ("intel_idle: Use ACPI _CST for processor models without C-state tables") Reported-by: Fab Stz Signed-off-by: Thomas Gleixner Tested-by: Fab Stz Cc: All applicable Closes: https://lore.kernel.org/all/10cf96aa-1276-4bd4-8966-c890377030c3@yahoo.fr Link: https://patch.msgid.link/87bjupfy7f.ffs@tglx Signed-off-by: Rafael J. Wysocki --- drivers/idle/intel_idle.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c index 118fe1d37c22..0fdb1d1316c4 100644 --- a/drivers/idle/intel_idle.c +++ b/drivers/idle/intel_idle.c @@ -56,6 +56,7 @@ #include #include #include +#include #include #define INTEL_IDLE_VERSION "0.5.1" @@ -1799,6 +1800,9 @@ static void __init intel_idle_init_cstates_acpi(struct cpuidle_driver *drv) if (intel_idle_state_needs_timer_stop(state)) state->flags |= CPUIDLE_FLAG_TIMER_STOP; + if (cx->type > ACPI_STATE_C1 && !boot_cpu_has(X86_FEATURE_NONSTOP_TSC)) + mark_tsc_unstable("TSC halts in idle"); + state->enter = intel_idle; state->enter_s2idle = intel_idle_s2idle; } -- 2.50.1 From cb380909ae3b1ebf14d6a455a4f92d7916d790cb Mon Sep 17 00:00:00 2001 From: Keith Busch Date: Thu, 27 Feb 2025 15:06:30 -0800 Subject: [PATCH 10/16] vhost: return task creation error instead of NULL Lets callers distinguish why the vhost task creation failed. No one currently cares why it failed, so no real runtime change from this patch, but that will not be the case for long. Signed-off-by: Keith Busch Message-ID: <20250227230631.303431-2-kbusch@meta.com> Reviewed-by: Mike Christie Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/mmu.c | 2 +- drivers/vhost/vhost.c | 2 +- kernel/vhost_task.c | 4 ++-- 3 files changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index d4ac4a1f8b81..18ca1ea6dc24 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -7471,7 +7471,7 @@ static void kvm_mmu_start_lpage_recovery(struct once *once) kvm_nx_huge_page_recovery_worker_kill, kvm, "kvm-nx-lpage-recovery"); - if (!nx_thread) + if (IS_ERR(nx_thread)) return; vhost_task_start(nx_thread); diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c index 9ac25d08f473..63612faeab72 100644 --- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -666,7 +666,7 @@ static struct vhost_worker *vhost_worker_create(struct vhost_dev *dev) vtsk = vhost_task_create(vhost_run_work_list, vhost_worker_killed, worker, name); - if (!vtsk) + if (IS_ERR(vtsk)) goto free_worker; mutex_init(&worker->mutex); diff --git a/kernel/vhost_task.c b/kernel/vhost_task.c index 8800f5acc007..2ef2e1b80091 100644 --- a/kernel/vhost_task.c +++ b/kernel/vhost_task.c @@ -133,7 +133,7 @@ struct vhost_task *vhost_task_create(bool (*fn)(void *), vtsk = kzalloc(sizeof(*vtsk), GFP_KERNEL); if (!vtsk) - return NULL; + return ERR_PTR(-ENOMEM); init_completion(&vtsk->exited); mutex_init(&vtsk->exit_mutex); vtsk->data = arg; @@ -145,7 +145,7 @@ struct vhost_task *vhost_task_create(bool (*fn)(void *), tsk = copy_process(NULL, 0, NUMA_NO_NODE, &args); if (IS_ERR(tsk)) { kfree(vtsk); - return NULL; + return ERR_PTR(PTR_ERR(tsk)); } vtsk->task = tsk; -- 2.50.1 From 916b7f42b3b3b539a71c204a9b49fdc4ca92cd82 Mon Sep 17 00:00:00 2001 From: Keith Busch Date: Thu, 27 Feb 2025 15:06:31 -0800 Subject: [PATCH 11/16] kvm: retry nx_huge_page_recovery_thread creation A VMM may send a non-fatal signal to its threads, including vCPU tasks, at any time, and thus may signal vCPU tasks during KVM_RUN. If a vCPU task receives the signal while its trying to spawn the huge page recovery vhost task, then KVM_RUN will fail due to copy_process() returning -ERESTARTNOINTR. Rework call_once() to mark the call complete if and only if the called function succeeds, and plumb the function's true error code back to the call_once() invoker. This provides userspace with the correct, non-fatal error code so that the VMM doesn't terminate the VM on -ENOMEM, and allows subsequent KVM_RUN a succeed by virtue of retrying creation of the NX huge page task. Co-developed-by: Sean Christopherson Signed-off-by: Sean Christopherson [implemented the kvm user side] Signed-off-by: Keith Busch Message-ID: <20250227230631.303431-3-kbusch@meta.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/mmu.c | 10 ++++----- include/linux/call_once.h | 47 ++++++++++++++++++++++++++++----------- 2 files changed, 38 insertions(+), 19 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 18ca1ea6dc24..8160870398b9 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -7460,7 +7460,7 @@ static bool kvm_nx_huge_page_recovery_worker(void *data) return true; } -static void kvm_mmu_start_lpage_recovery(struct once *once) +static int kvm_mmu_start_lpage_recovery(struct once *once) { struct kvm_arch *ka = container_of(once, struct kvm_arch, nx_once); struct kvm *kvm = container_of(ka, struct kvm, arch); @@ -7472,12 +7472,13 @@ static void kvm_mmu_start_lpage_recovery(struct once *once) kvm, "kvm-nx-lpage-recovery"); if (IS_ERR(nx_thread)) - return; + return PTR_ERR(nx_thread); vhost_task_start(nx_thread); /* Make the task visible only once it is fully started. */ WRITE_ONCE(kvm->arch.nx_huge_page_recovery_thread, nx_thread); + return 0; } int kvm_mmu_post_init_vm(struct kvm *kvm) @@ -7485,10 +7486,7 @@ int kvm_mmu_post_init_vm(struct kvm *kvm) if (nx_hugepage_mitigation_hard_disabled) return 0; - call_once(&kvm->arch.nx_once, kvm_mmu_start_lpage_recovery); - if (!kvm->arch.nx_huge_page_recovery_thread) - return -ENOMEM; - return 0; + return call_once(&kvm->arch.nx_once, kvm_mmu_start_lpage_recovery); } void kvm_mmu_pre_destroy_vm(struct kvm *kvm) diff --git a/include/linux/call_once.h b/include/linux/call_once.h index 6261aa0b3fb0..13cd6469e7e5 100644 --- a/include/linux/call_once.h +++ b/include/linux/call_once.h @@ -26,20 +26,41 @@ do { \ __once_init((once), #once, &__key); \ } while (0) -static inline void call_once(struct once *once, void (*cb)(struct once *)) +/* + * call_once - Ensure a function has been called exactly once + * + * @once: Tracking struct + * @cb: Function to be called + * + * If @once has never completed successfully before, call @cb and, if + * it returns a zero or positive value, mark @once as completed. Return + * the value returned by @cb + * + * If @once has completed succesfully before, return 0. + * + * The call to @cb is implicitly surrounded by a mutex, though for + * efficiency the * function avoids taking it after the first call. + */ +static inline int call_once(struct once *once, int (*cb)(struct once *)) { - /* Pairs with atomic_set_release() below. */ - if (atomic_read_acquire(&once->state) == ONCE_COMPLETED) - return; - - guard(mutex)(&once->lock); - WARN_ON(atomic_read(&once->state) == ONCE_RUNNING); - if (atomic_read(&once->state) != ONCE_NOT_STARTED) - return; - - atomic_set(&once->state, ONCE_RUNNING); - cb(once); - atomic_set_release(&once->state, ONCE_COMPLETED); + int r, state; + + /* Pairs with atomic_set_release() below. */ + if (atomic_read_acquire(&once->state) == ONCE_COMPLETED) + return 0; + + guard(mutex)(&once->lock); + state = atomic_read(&once->state); + if (unlikely(state != ONCE_NOT_STARTED)) + return WARN_ON_ONCE(state != ONCE_COMPLETED) ? -EINVAL : 0; + + atomic_set(&once->state, ONCE_RUNNING); + r = cb(once); + if (r < 0) + atomic_set(&once->state, ONCE_NOT_STARTED); + else + atomic_set_release(&once->state, ONCE_COMPLETED); + return r; } #endif /* _LINUX_CALL_ONCE_H */ -- 2.50.1 From a2f925a2f62254119cdaa360cfc9c0424bccd531 Mon Sep 17 00:00:00 2001 From: Niklas Cassel Date: Fri, 28 Feb 2025 13:26:04 +0100 Subject: [PATCH 12/16] Revert "ata: libata-core: Add ATA_QUIRK_NOLPM for Samsung SSD 870 QVO drives" This reverts commit cc77e2ce187d26cc66af3577bf896d7410eb25ab. It was reported that adding ATA_QUIRK_NOLPM for Samsung SSD 870 QVO drives breaks entering lower package states for certain systems. It turns out that Samsung SSD 870 QVO actually has working LPM when using a recent SSD firmware version. The author of commit cc77e2ce187d ("ata: libata-core: Add ATA_QUIRK_NOLPM for Samsung SSD 870 QVO drives") reported himself that only older SSD firmware versions have broken LPM: https://lore.kernel.org/stable/93c10d38-718c-459d-84a5-4d87680b4da7@debian.org/ Unfortunately, he did not specify which older firmware version he was using which had broken LPM. Let's revert this quirk, which has FW version field specified as NULL (which means that it applies for all Samsung SSD 870 QVO firmware versions) for now. Once the author reports which older firmware version(s) that are broken, we can create a more fine grained quirk, which populates the FW version field accordingly. Fixes: cc77e2ce187d ("ata: libata-core: Add ATA_QUIRK_NOLPM for Samsung SSD 870 QVO drives") Reported-by: Dieter Mummenschanz Closes: https://bugzilla.kernel.org/show_bug.cgi?id=219747 Link: https://lore.kernel.org/r/20250228122603.91814-2-cassel@kernel.org Signed-off-by: Niklas Cassel --- drivers/ata/libata-core.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c index 63ec2f218431..c085dd81ebe7 100644 --- a/drivers/ata/libata-core.c +++ b/drivers/ata/libata-core.c @@ -4143,10 +4143,6 @@ static const struct ata_dev_quirks_entry __ata_dev_quirks[] = { { "Samsung SSD 860*", NULL, ATA_QUIRK_NO_NCQ_TRIM | ATA_QUIRK_ZERO_AFTER_TRIM | ATA_QUIRK_NO_NCQ_ON_ATI }, - { "Samsung SSD 870 QVO*", NULL, ATA_QUIRK_NO_NCQ_TRIM | - ATA_QUIRK_ZERO_AFTER_TRIM | - ATA_QUIRK_NO_NCQ_ON_ATI | - ATA_QUIRK_NOLPM }, { "Samsung SSD 870*", NULL, ATA_QUIRK_NO_NCQ_TRIM | ATA_QUIRK_ZERO_AFTER_TRIM | ATA_QUIRK_NO_NCQ_ON_ATI }, -- 2.50.1 From 7eb172143d5508b4da468ed59ee857c6e5e01da6 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 2 Mar 2025 11:48:20 -0800 Subject: [PATCH 13/16] Linux 6.14-rc5 --- Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/Makefile b/Makefile index 30dab4c8b012..70bdbf2218fc 100644 --- a/Makefile +++ b/Makefile @@ -2,7 +2,7 @@ VERSION = 6 PATCHLEVEL = 14 SUBLEVEL = 0 -EXTRAVERSION = -rc4 +EXTRAVERSION = -rc5 NAME = Baby Opossum Posse # *DOCUMENTATION* -- 2.50.1 From fd5ba38390c59e1c147480ae49b6133c4ac24001 Mon Sep 17 00:00:00 2001 From: "Masami Hiramatsu (Google)" Date: Wed, 26 Feb 2025 15:19:18 +0900 Subject: [PATCH 14/16] tracing: probe-events: Remove unused MAX_ARG_BUF_LEN macro Commit 18b1e870a496 ("tracing/probes: Add $arg* meta argument for all function args") introduced MAX_ARG_BUF_LEN but it is not used. Remove it. Link: https://lore.kernel.org/all/174055075876.4079315.8805416872155957588.stgit@mhiramat.tok.corp.google.com/ Fixes: 18b1e870a496 ("tracing/probes: Add $arg* meta argument for all function args") Signed-off-by: Masami Hiramatsu (Google) Reviewed-by: Steven Rostedt (Google) --- kernel/trace/trace_probe.h | 1 - 1 file changed, 1 deletion(-) diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h index c47ca002347a..96792bc4b092 100644 --- a/kernel/trace/trace_probe.h +++ b/kernel/trace/trace_probe.h @@ -36,7 +36,6 @@ #define MAX_BTF_ARGS_LEN 128 #define MAX_DENTRY_ARGS_LEN 256 #define MAX_STRING_SIZE PATH_MAX -#define MAX_ARG_BUF_LEN (MAX_TRACE_ARGS * MAX_ARG_NAME_LEN) /* Reserved field names */ #define FIELD_STRING_IP "__probe_ip" -- 2.50.1 From 3d252160b818045f3a152b13756f6f37ca34639d Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Tue, 4 Mar 2025 13:51:38 +0000 Subject: [PATCH 15/16] fs/pipe: Read pipe->{head,tail} atomically outside pipe->mutex pipe_readable(), pipe_writable(), and pipe_poll() can read "pipe->head" and "pipe->tail" outside of "pipe->mutex" critical section. When the head and the tail are read individually in that order, there is a window for interruption between the two reads in which both the head and the tail can be updated by concurrent readers and writers. One of the problematic scenarios observed with hackbench running multiple groups on a large server on a particular pipe inode is as follows: pipe->head = 36 pipe->tail = 36 hackbench-118762 [057] ..... 1029.550548: pipe_write: *wakes up: pipe not full* hackbench-118762 [057] ..... 1029.550548: pipe_write: head: 36 -> 37 [tail: 36] hackbench-118762 [057] ..... 1029.550548: pipe_write: *wake up next reader 118740* hackbench-118762 [057] ..... 1029.550548: pipe_write: *wake up next writer 118768* hackbench-118768 [206] ..... 1029.55055X: pipe_write: *writer wakes up* hackbench-118768 [206] ..... 1029.55055X: pipe_write: head = READ_ONCE(pipe->head) [37] ... CPU 206 interrupted (exact wakeup was not traced but 118768 did read head at 37 in traces) hackbench-118740 [057] ..... 1029.550558: pipe_read: *reader wakes up: pipe is not empty* hackbench-118740 [057] ..... 1029.550558: pipe_read: tail: 36 -> 37 [head = 37] hackbench-118740 [057] ..... 1029.550559: pipe_read: *pipe is empty; wakeup writer 118768* hackbench-118740 [057] ..... 1029.550559: pipe_read: *sleeps* hackbench-118766 [185] ..... 1029.550592: pipe_write: *New writer comes in* hackbench-118766 [185] ..... 1029.550592: pipe_write: head: 37 -> 38 [tail: 37] hackbench-118766 [185] ..... 1029.550592: pipe_write: *wakes up reader 118766* hackbench-118740 [185] ..... 1029.550598: pipe_read: *reader wakes up; pipe not empty* hackbench-118740 [185] ..... 1029.550599: pipe_read: tail: 37 -> 38 [head: 38] hackbench-118740 [185] ..... 1029.550599: pipe_read: *pipe is empty* hackbench-118740 [185] ..... 1029.550599: pipe_read: *reader sleeps; wakeup writer 118768* ... CPU 206 switches back to writer hackbench-118768 [206] ..... 1029.550601: pipe_write: tail = READ_ONCE(pipe->tail) [38] hackbench-118768 [206] ..... 1029.550601: pipe_write: pipe_full()? (u32)(37 - 38) >= 16? Yes hackbench-118768 [206] ..... 1029.550601: pipe_write: *writer goes back to sleep* [ Tasks 118740 and 118768 can then indefinitely wait on each other. ] The unsigned arithmetic in pipe_occupancy() wraps around when "pipe->tail > pipe->head" leading to pipe_full() returning true despite the pipe being empty. The case of genuine wraparound of "pipe->head" is handled since pipe buffer has data allowing readers to make progress until the pipe->tail wraps too after which the reader will wakeup a sleeping writer, however, mistaking the pipe to be full when it is in fact empty can lead to readers and writers waiting on each other indefinitely. This issue became more problematic and surfaced as a hang in hackbench after the optimization in commit aaec5a95d596 ("pipe_read: don't wake up the writer if the pipe is still full") significantly reduced the number of spurious wakeups of writers that had previously helped mask the issue. To avoid missing any updates between the reads of "pipe->head" and "pipe->write", unionize the two with a single unsigned long "pipe->head_tail" member that can be loaded atomically. Using "pipe->head_tail" to read the head and the tail ensures the lockless checks do not miss any updates to the head or the tail and since those two are only updated under "pipe->mutex", it ensures that the head is always ahead of, or equal to the tail resulting in correct calculations. [ prateek: commit log, testing on x86 platforms. ] Reported-and-debugged-by: Swapnil Sapkal Closes: https://lore.kernel.org/lkml/e813814e-7094-4673-bc69-731af065a0eb@amd.com/ Reported-by: Alexey Gladkov Closes: https://lore.kernel.org/all/Z8Wn0nTvevLRG_4m@example.org/ Fixes: 8cefc107ca54 ("pipe: Use head and tail pointers for the ring, not cursor and length") Tested-by: Swapnil Sapkal Reviewed-by: Oleg Nesterov Tested-by: Alexey Gladkov Signed-off-by: K Prateek Nayak Signed-off-by: Linus Torvalds --- fs/pipe.c | 19 ++++++++----------- include/linux/pipe_fs_i.h | 39 +++++++++++++++++++++++++++++++++++++-- 2 files changed, 45 insertions(+), 13 deletions(-) diff --git a/fs/pipe.c b/fs/pipe.c index ce1af7592780..e8e6698f3698 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -210,11 +210,10 @@ static const struct pipe_buf_operations anon_pipe_buf_ops = { /* Done while waiting without holding the pipe lock - thus the READ_ONCE() */ static inline bool pipe_readable(const struct pipe_inode_info *pipe) { - unsigned int head = READ_ONCE(pipe->head); - unsigned int tail = READ_ONCE(pipe->tail); + union pipe_index idx = { .head_tail = READ_ONCE(pipe->head_tail) }; unsigned int writers = READ_ONCE(pipe->writers); - return !pipe_empty(head, tail) || !writers; + return !pipe_empty(idx.head, idx.tail) || !writers; } static inline unsigned int pipe_update_tail(struct pipe_inode_info *pipe, @@ -417,11 +416,10 @@ static inline int is_packetized(struct file *file) /* Done while waiting without holding the pipe lock - thus the READ_ONCE() */ static inline bool pipe_writable(const struct pipe_inode_info *pipe) { - unsigned int head = READ_ONCE(pipe->head); - unsigned int tail = READ_ONCE(pipe->tail); + union pipe_index idx = { .head_tail = READ_ONCE(pipe->head_tail) }; unsigned int max_usage = READ_ONCE(pipe->max_usage); - return !pipe_full(head, tail, max_usage) || + return !pipe_full(idx.head, idx.tail, max_usage) || !READ_ONCE(pipe->readers); } @@ -659,7 +657,7 @@ pipe_poll(struct file *filp, poll_table *wait) { __poll_t mask; struct pipe_inode_info *pipe = filp->private_data; - unsigned int head, tail; + union pipe_index idx; /* Epoll has some historical nasty semantics, this enables them */ WRITE_ONCE(pipe->poll_usage, true); @@ -680,19 +678,18 @@ pipe_poll(struct file *filp, poll_table *wait) * if something changes and you got it wrong, the poll * table entry will wake you up and fix it. */ - head = READ_ONCE(pipe->head); - tail = READ_ONCE(pipe->tail); + idx.head_tail = READ_ONCE(pipe->head_tail); mask = 0; if (filp->f_mode & FMODE_READ) { - if (!pipe_empty(head, tail)) + if (!pipe_empty(idx.head, idx.tail)) mask |= EPOLLIN | EPOLLRDNORM; if (!pipe->writers && filp->f_pipe != pipe->w_counter) mask |= EPOLLHUP; } if (filp->f_mode & FMODE_WRITE) { - if (!pipe_full(head, tail, pipe->max_usage)) + if (!pipe_full(idx.head, idx.tail, pipe->max_usage)) mask |= EPOLLOUT | EPOLLWRNORM; /* * Most Unices do not set EPOLLERR for FIFOs but on Linux they diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h index 8ff23bf5a819..3cc4f8eab853 100644 --- a/include/linux/pipe_fs_i.h +++ b/include/linux/pipe_fs_i.h @@ -31,6 +31,33 @@ struct pipe_buffer { unsigned long private; }; +/* + * Really only alpha needs 32-bit fields, but + * might as well do it for 64-bit architectures + * since that's what we've historically done, + * and it makes 'head_tail' always be a simple + * 'unsigned long'. + */ +#ifdef CONFIG_64BIT +typedef unsigned int pipe_index_t; +#else +typedef unsigned short pipe_index_t; +#endif + +/* + * We have to declare this outside 'struct pipe_inode_info', + * but then we can't use 'union pipe_index' for an anonymous + * union, so we end up having to duplicate this declaration + * below. Annoying. + */ +union pipe_index { + unsigned long head_tail; + struct { + pipe_index_t head; + pipe_index_t tail; + }; +}; + /** * struct pipe_inode_info - a linux kernel pipe * @mutex: mutex protecting the whole thing @@ -58,8 +85,16 @@ struct pipe_buffer { struct pipe_inode_info { struct mutex mutex; wait_queue_head_t rd_wait, wr_wait; - unsigned int head; - unsigned int tail; + + /* This has to match the 'union pipe_index' above */ + union { + unsigned long head_tail; + struct { + pipe_index_t head; + pipe_index_t tail; + }; + }; + unsigned int max_usage; unsigned int ring_size; unsigned int nr_accounted; -- 2.50.1 From c27c66afc449b80f3b4b84d123358c0248f2cf63 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Wed, 5 Mar 2025 07:08:09 -1000 Subject: [PATCH 16/16] fs/pipe: Fix pipe_occupancy() with 16-bit indexes The pipe_occupancy() logic implicitly relied on the natural unsigned modulo arithmetic in C, but that doesn't work for the new 'pipe_index_t' case, since any arithmetic will be done in 'int' (and here we had also made it 'unsigned int' due to the function call boundary). So make the modulo arithmetic explicit by casting the result to the proper type. Cc: Oleg Nesterov Cc: Mateusz Guzik Cc: Manfred Spraul Cc: Christian Brauner Cc: Swapnil Sapkal Cc: Alexey Gladkov Cc: K Prateek Nayak Link: https://lore.kernel.org/all/CAHk-=wjyHsGLx=rxg6PKYBNkPYAejgo7=CbyL3=HGLZLsAaJFQ@mail.gmail.com/ Fixes: 3d252160b818 ("fs/pipe: Read pipe->{head,tail} atomically outside pipe->mutex") Signed-off-by: Linus Torvalds --- include/linux/pipe_fs_i.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/pipe_fs_i.h b/include/linux/pipe_fs_i.h index 3cc4f8eab853..1f013ed7577e 100644 --- a/include/linux/pipe_fs_i.h +++ b/include/linux/pipe_fs_i.h @@ -192,7 +192,7 @@ static inline bool pipe_empty(unsigned int head, unsigned int tail) */ static inline unsigned int pipe_occupancy(unsigned int head, unsigned int tail) { - return head - tail; + return (pipe_index_t)(head - tail); } /** -- 2.50.1