* Re: [PATCH 1/3] rv/reactors: fix lockdep "Invalid wait context" in rv_react()
From: Thomas Weißschuh @ 2026-07-08 15:47 UTC (permalink / raw)
To: Gabriele Monaco; +Cc: wen.yang, Nam Cao, linux-trace-kernel, linux-kernel
In-Reply-To: <3c53f741559f834986e976b524c5ded90bbd5627.camel@redhat.com>
On Mon, Jul 06, 2026 at 04:02:08PM +0200, Gabriele Monaco wrote:
> On Tue, 2026-06-23 at 11:38 +0200, Thomas Weißschuh wrote:
> > This now allows reactors to take (raw) spinlocks. The original idea was
> > to not allow that as a reactor can be called from LD_WAIT_FREE context.
> > So I am not sure this is the right fix. Not that I have a better one
> > available right now.
>
> As far as I understand it, LD_WAIT_FREE is fairly impossible to apply on
> preemptible code (here we see it hit by an interrupt).
>
> Since we kind of have to allow raw spinlock to avoid this (even if we don't take
> them explicitly), why wouldn't a reactor ever be allowed to take raw spinlocks?
>
> Technically it wouldn't be wrong to take locks from RV monitors, although most
> monitors don't do it explicitly.
> If we ever happen to take the wrong lock explicitly from a reactor triggered by
> a nasty event (e.g. sched_switch), I believe lockdep would still be complaining
> down that path, so we probably don't need to be too strict in rv_react().
>
> Obviously we don't want to disable interrutps for LD_WAIT_FREE to hold either.
>
> Am I missing something?
No, I was just very confused.
Let's go ahead with this.
Thomas
^ permalink raw reply
* Re: [PATCH v1] tracing/remotes: Fix leak in trace_remote_alloc_buffer() error path
From: Steven Rostedt @ 2026-07-08 16:59 UTC (permalink / raw)
To: Vincent Donnefort
Cc: mhiramat, mathieu.desnoyers, linux-trace-kernel, kernel-team,
linux-kernel, Sashiko
In-Reply-To: <20260708133201.295072-1-vdonnefort@google.com>
On Wed, 8 Jul 2026 14:32:01 +0100
Vincent Donnefort <vdonnefort@google.com> wrote:
> If page allocation fails in trace_remote_alloc_buffer(), desc->nr_cpus
> is not yet incremented for the current CPU. As a consequence, on error,
> half-allocated rb_desc will not be freed in trace_remote_free_buffer().
>
> Include the failing CPU in desc->nr_cpus before going to the error path.
>
Looks like Sashiko found other issues you may want to address:
https://sashiko.dev/#/patchset/20260708133201.295072-1-vdonnefort%40google.com
-- Steve
> Fixes: 96e43537af54 ("tracing: Introduce trace remotes")
> Reported-by: Sashiko <sashiko-bot@kernel.org>
> Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
>
> diff --git a/kernel/trace/trace_remote.c b/kernel/trace/trace_remote.c
> index 2a6cc000ec98..62d3d431c309 100644
> --- a/kernel/trace/trace_remote.c
> +++ b/kernel/trace/trace_remote.c
> @@ -1008,8 +1008,10 @@ int trace_remote_alloc_buffer(struct trace_buffer_desc *desc, size_t desc_size,
>
> for (id = 0; id < nr_pages; id++) {
> rb_desc->page_va[id] = (unsigned long)__get_free_page(GFP_KERNEL);
> - if (!rb_desc->page_va[id])
> + if (!rb_desc->page_va[id]) {
> + desc->nr_cpus++; /* Free this partially-allocated rb_desc */
> goto err;
> + }
>
> rb_desc->nr_page_va++;
> }
>
> base-commit: 8cdeaa50eae8dad34885515f62559ee83e7e8dda
^ permalink raw reply
* [PATCH] selftests/ftrace: Fix reading enabled_functions in add_remove_fprobe_module test
From: Steven Rostedt @ 2026-07-08 19:32 UTC (permalink / raw)
To: LKML, Linux Trace Kernel, linux-kselftest
Cc: Masami Hiramatsu, Mathieu Desnoyers, Shuah Khan, Shuah Khan
From: Steven Rostedt <rostedt@goodmis.org>
The add_remove_fprobe_module test checks the number of functions added to
the enabled_functions file to make sure that the functions added or
removed is as expected. The issue is that it expects this file to be empty
on start up.
Now that systemd uses BPF that attaches to functions via ftrace, this file
is not empty in several systems:
# cat /sys/kernel/tracing/enabled_functions
bpf_lsm_file_open (1) R D M tramp: ftrace_regs_caller+0x0/0x61 (call_direct_funcs+0x0/0x50)
direct(jmp)-->bpf_trampoline_6442529439+0x0/0xe9
Change the test to read the number of lines in enabled_functions at the
start of the test and subtract that from the value of the count for the
checks within the test.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
.../dynevent/add_remove_fprobe_module.tc | 27 ++++++++++++-------
1 file changed, 18 insertions(+), 9 deletions(-)
diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_module.tc b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_module.tc
index 2915206777b6..89660a9adf44 100644
--- a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_module.tc
+++ b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_module.tc
@@ -16,23 +16,32 @@ echo > dynamic_events
FUNC1='foo_bar*'
FUNC2='vfs_read'
+:;: "Save enabled functions count" ;:
+ecount=`cat enabled_functions | wc -l`
+
+count_enabled_functions() {
+ count=`cat enabled_functions | wc -l`
+ count=$(($count-$ecount))
+ echo $count
+}
+
:;: "Add an event on the test module" ;:
echo "f:test1 $FUNC1" >> dynamic_events
echo 1 > events/fprobes/test1/enable
:;: "Ensure it is enabled" ;:
-funcs=`cat enabled_functions | wc -l`
+funcs=`count_enabled_functions`
test $funcs -ne 0
:;: "Check the enabled_functions is cleared on unloading" ;:
rmmod trace-events-sample
-funcs=`cat enabled_functions | wc -l`
+funcs=`count_enabled_functions`
test $funcs -eq 0
:;: "Check it is kept clean" ;:
modprobe trace-events-sample
echo 1 > events/fprobes/test1/enable || echo "OK"
-funcs=`cat enabled_functions | wc -l`
+funcs=`count_enabled_functions`
test $funcs -eq 0
:;: "Add another event not on the test module" ;:
@@ -40,19 +49,19 @@ echo "f:test2 $FUNC2" >> dynamic_events
echo 1 > events/fprobes/test2/enable
:;: "Ensure it is enabled" ;:
-ofuncs=`cat enabled_functions | wc -l`
+ofuncs=`count_enabled_functions`
test $ofuncs -ne 0
:;: "Disable and remove the first event"
echo 0 > events/fprobes/test1/enable
echo "-:fprobes/test1" >> dynamic_events
-funcs=`cat enabled_functions | wc -l`
+funcs=`count_enabled_functions`
test $ofuncs -eq $funcs
:;: "Disable and remove other events" ;:
echo 0 > events/fprobes/enable
echo > dynamic_events
-funcs=`cat enabled_functions | wc -l`
+funcs=`count_enabled_functions`
test $funcs -eq 0
rmmod trace-events-sample
@@ -63,12 +72,12 @@ echo "f:test1 $FUNC1" >> dynamic_events
echo 1 > events/fprobes/test1/enable
echo "f:test2 $FUNC2" >> dynamic_events
echo 1 > events/fprobes/test2/enable
-ofuncs=`cat enabled_functions | wc -l`
+ofuncs=`count_enabled_functions`
test $ofuncs -ne 0
:;: "Unload module (ftrace entry should be removed)" ;:
rmmod trace-events-sample
-funcs=`cat enabled_functions | wc -l`
+funcs=`count_enabled_functions`
test $funcs -ne 0
test $ofuncs -ne $funcs
@@ -77,7 +86,7 @@ echo 0 > events/fprobes/test2/enable
echo "-:fprobes/test2" >> dynamic_events
:;: "Ensure ftrace is disabled." ;:
-funcs=`cat enabled_functions | wc -l`
+funcs=`count_enabled_functions`
test $funcs -eq 0
echo 0 > events/fprobes/enable
--
2.53.0
^ permalink raw reply related
* Re: [PATCH] selftests/tracing: Have trigger-hist-poll.tc use sched_process_exit
From: Steven Rostedt @ 2026-07-08 20:35 UTC (permalink / raw)
To: LKML, Linux Trace Kernel, linux-kselftest
Cc: Masami Hiramatsu, Mathieu Desnoyers, Shuah Khan, Shuah Khan
In-Reply-To: <20260708163436.058cc3df@gandalf.local.home>
On Wed, 8 Jul 2026 16:34:36 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:
> From: Steven Rostedt <rostedt@goodmis.org>
>
> Currently trigger-hist-poll.tc uses sched_process_free to test the polling
> of the histogram file. The way it does that is to run sleep, then execute
> the poll.c code that polls on the sched_process_free for up to 4 seconds
> to test that when sleep triggers the sched_process_free trace event, it
> will update the histogram and wake the poll.c code up.
>
> The issue is that sched_process_free trace event is called by
> delayed_put_task_struct() which is called after a RCU grace period has
> ended. If CONFIG_RCU_LAZY is enabled, RCU callbacks are batched together
> and do not execute right away. This causes the delayed_put_task_struct()
> to be called after the poll.c function finishes and it will report an
> error that it did not wake up on the event. That's because the event
> didn't trigger during its wait time.
>
> Use sched_process_exit instead, which is called when a process exits and
> doesn't depend on RCU callbacks that may be delayed.
>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> ---
I forgot to mention that I tested this with and without CONFIG_RCU_LAZY.
With that config disabled, the test passes. With it enabled, it always
fails.
-- Steve
^ permalink raw reply
* Re: [PATCH] selftests/tracing: Have trigger-hist-poll.tc use sched_process_exit
From: Steven Rostedt @ 2026-07-08 20:37 UTC (permalink / raw)
To: LKML, Linux Trace Kernel, linux-kselftest
Cc: Masami Hiramatsu, Mathieu Desnoyers, Shuah Khan, Shuah Khan
In-Reply-To: <20260708163539.1e1d845d@gandalf.local.home>
On Wed, 8 Jul 2026 16:35:39 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:
> I forgot to mention that I tested this with and without CONFIG_RCU_LAZY.
> With that config disabled, the test passes. With it enabled, it always
> fails.
And I also traced it with:
trace-cmd set -p function_graph -l event_hist_poll -O funcgraph-retval
and it shows the sched_process_free being called for the sleep process
*after* the poll finishes.
-- Steve
^ permalink raw reply
* [PATCH] selftests/tracing: Have trigger-hist-poll.tc use sched_process_exit
From: Steven Rostedt @ 2026-07-08 20:34 UTC (permalink / raw)
To: LKML, Linux Trace Kernel, linux-kselftest
Cc: Masami Hiramatsu, Mathieu Desnoyers, Shuah Khan, Shuah Khan
From: Steven Rostedt <rostedt@goodmis.org>
Currently trigger-hist-poll.tc uses sched_process_free to test the polling
of the histogram file. The way it does that is to run sleep, then execute
the poll.c code that polls on the sched_process_free for up to 4 seconds
to test that when sleep triggers the sched_process_free trace event, it
will update the histogram and wake the poll.c code up.
The issue is that sched_process_free trace event is called by
delayed_put_task_struct() which is called after a RCU grace period has
ended. If CONFIG_RCU_LAZY is enabled, RCU callbacks are batched together
and do not execute right away. This causes the delayed_put_task_struct()
to be called after the poll.c function finishes and it will report an
error that it did not wake up on the event. That's because the event
didn't trigger during its wait time.
Use sched_process_exit instead, which is called when a process exits and
doesn't depend on RCU callbacks that may be delayed.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
.../selftests/ftrace/test.d/trigger/trigger-hist-poll.tc | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-poll.tc b/tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-poll.tc
index 8d275e3238d9..04eb8546fc07 100644
--- a/tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-poll.tc
+++ b/tools/testing/selftests/ftrace/test.d/trigger/trigger-hist-poll.tc
@@ -1,7 +1,7 @@
#!/bin/sh
# SPDX-License-Identifier: GPL-2.0
# description: event trigger - test poll wait on histogram
-# requires: set_event events/sched/sched_process_free/trigger events/sched/sched_process_free/hist
+# requires: set_event events/sched/sched_process_exit/trigger events/sched/sched_process_exit/hist
# flags: instance
POLL=${FTRACETEST_ROOT}/poll
@@ -11,7 +11,7 @@ if [ ! -x ${POLL} ]; then
exit_unresolved
fi
-EVENT=events/sched/sched_process_free/
+EVENT=events/sched/sched_process_exit/
# Check poll ops is supported. Before implementing poll on hist file, it
# returns soon with POLLIN | POLLOUT, but not POLLPRI.
--
2.53.0
^ permalink raw reply related
* Re: [PATCH v3 01/11] dt-bindings: reserved-memory: Document Tegra VPR
From: Rob Herring @ 2026-07-08 21:18 UTC (permalink / raw)
To: Thierry Reding
Cc: Christian Borntraeger, Rasmus Villemoes, dri-devel,
David Hildenbrand, Yury Norov, linux-media, linux-kernel,
Robin Murphy, Simona Vetter, linux-trace-kernel,
Krzysztof Kozlowski, Christian König, linux-mm, Russell King,
Will Deacon, Masami Hiramatsu, David Airlie, Vasily Gorbik,
Benjamin Gaignard, linaro-mm-sig, Heiko Carstens, Sumit Semwal,
Thierry Reding, Maxime Ripard, Thierry Reding, John Stultz,
Luca Ceresoli, Vlastimil Babka, Brian Starkey, Mikko Perttunen,
Michal Hocko, Steven Rostedt, Jonathan Hunter, Maarten Lankhorst,
Sowjanya Komatineni, Suren Baghdasaryan, linux-arm-kernel,
linux-s390, devicetree, Liam R. Howlett, linux-tegra,
Catalin Marinas, Marek Szyprowski, Conor Dooley,
Thomas Zimmermann, Andrew Morton, Gerald Schaefer,
Alexander Gordeev, Lorenzo Stoakes, T.J. Mercier,
Mathieu Desnoyers, iommu, Mike Rapoport, Sven Schnelle
In-Reply-To: <akZde-8lFvf8rPji@orome>
On Thu, Jul 2, 2026 at 7:58 AM Thierry Reding <thierry.reding@kernel.org> wrote:
>
> On Wed, Jul 01, 2026 at 02:53:10PM -0500, Rob Herring (Arm) wrote:
> >
> > On Wed, 01 Jul 2026 18:08:12 +0200, Thierry Reding wrote:
> > > From: Thierry Reding <treding@nvidia.com>
> > >
> > > The Video Protection Region (VPR) found on NVIDIA Tegra chips is a
> > > region of memory that is protected from CPU accesses. It is used to
> > > decode and play back DRM protected content.
> > >
> > > It is a standard reserved memory region that can exist in two forms:
> > > static VPR where the base address and size are fixed (uses the "reg"
> > > property to describe the memory) and a resizable VPR where only the
> > > size is known upfront and the OS can allocate it wherever it can be
> > > accomodated.
> > >
> > > Reviewed-by: Rob Herring (Arm) <robh@kernel.org>
> > > Signed-off-by: Thierry Reding <treding@nvidia.com>
> > > ---
> > > Changes in v2:
> > > - add examples for fixed and resizable VPR
> > > ---
> > > .../nvidia,tegra-video-protection-region.yaml | 76 ++++++++++++++++++++++
> > > 1 file changed, 76 insertions(+)
> > >
> >
> > My bot found errors running 'make dt_binding_check' on your patch:
> >
> > yamllint warnings/errors:
> >
> > dtschema/dtc warnings/errors:
> > /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/reserved-memory/nvidia,tegra-video-protection-region.example.dtb: protected@2a8000000 (nvidia,tegra-video-protection-region): reg: [[2, 2818572288], [0, 1879048192]] is too long
> > from schema $id: http://devicetree.org/schemas/reserved-memory/nvidia,tegra-video-protection-region.yaml
> > /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/reserved-memory/nvidia,tegra-video-protection-region.example.dtb: protected@2a8000000 (nvidia,tegra-video-protection-region): Unevaluated properties are not allowed ('no-map', 'reg' were unexpected)
> > from schema $id: http://devicetree.org/schemas/reserved-memory/nvidia,tegra-video-protection-region.yaml
>
> Any ideas why that second error shows up? It turns out that it goes away
> when the first one is fixed (which admittedly is a stupid mistake), but
> I spent quite a bit of time looking for a fix before realizing that it's
> only a side-effect of the first.
If a property fails validation in a referenced schema, then everything
in that referenced schema is considered not evaluated. So then
unevaluatedProperties is applied to the properties only in the
referenced schema. That's why 'no-map' is also unevaluated. Just a
quirk of how json-schema works...
Rob
^ permalink raw reply
* Re: [PATCH v3 06/11] mm/cma: Allow dynamically creating CMA areas
From: T.J. Mercier @ 2026-07-08 23:49 UTC (permalink / raw)
To: Thierry Reding
Cc: Rob Herring, Krzysztof Kozlowski, Conor Dooley, Jonathan Hunter,
David Airlie, Simona Vetter, Maarten Lankhorst, Maxime Ripard,
Thomas Zimmermann, Sowjanya Komatineni, Luca Ceresoli,
Mikko Perttunen, Yury Norov, Rasmus Villemoes, Russell King,
Alexander Gordeev, Gerald Schaefer, Heiko Carstens, Vasily Gorbik,
Christian Borntraeger, Sven Schnelle, Andrew Morton,
David Hildenbrand, Lorenzo Stoakes, Liam R. Howlett,
Vlastimil Babka, Mike Rapoport, Suren Baghdasaryan, Michal Hocko,
Marek Szyprowski, Robin Murphy, Sumit Semwal, Benjamin Gaignard,
Brian Starkey, John Stultz, Christian König, Steven Rostedt,
Masami Hiramatsu, Mathieu Desnoyers, Catalin Marinas, Will Deacon,
Thierry Reding, devicetree, linux-tegra, linux-kernel, dri-devel,
linux-media, linux-arm-kernel, linux-s390, linux-mm, iommu,
linaro-mm-sig, linux-trace-kernel, Thierry Reding
In-Reply-To: <20260701-tegra-vpr-v3-6-d80f7b871bb4@nvidia.com>
On Wed, Jul 1, 2026 at 9:09 AM Thierry Reding <thierry.reding@kernel.org> wrote:
>
> From: Thierry Reding <treding@nvidia.com>
>
> There is no technical reason why there should be a limited number of CMA
> regions, so extract some code into helpers and use them to create extra
> functions (cma_create() and cma_free()) that allow creating and freeing,
> respectively, CMA regions dynamically at runtime.
>
> The static array of CMA areas cannot be replaced by dynamically created
> areas because for many of them, allocation must not fail and some cases
> may need to initialize them before the slab allocator is even available.
> To account for this, keep these "early" areas in a separate list and
> track the dynamic areas in a separate list.
Hi, It looks like you'll also need to update the CMA dma-buf heap's
add_cma_heaps init function so that it adds all the CMA areas, not
just the early ones.
>
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
> Changes in v3:
> - rebase on top of recent linux-next, update kernel/dma/contiguous.c
> - use kzalloc_obj() instead of kzalloc() with sizeof()
>
> Changes in v2:
> - rename fixed number of CMA areas to reflect their main use
> - account for pages in dynamically allocated regions
> ---
> arch/arm/mm/dma-mapping.c | 2 +-
> arch/s390/mm/init.c | 2 +-
> include/linux/cma.h | 8 +-
> kernel/dma/contiguous.c | 2 +-
> mm/cma.c | 187 +++++++++++++++++++++++++++++++++++++---------
> mm/cma.h | 5 +-
> 6 files changed, 165 insertions(+), 41 deletions(-)
>
> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index f9bc53b60f99..934952ab2102 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -254,7 +254,7 @@ struct dma_contig_early_reserve {
> unsigned long size;
> };
>
> -static struct dma_contig_early_reserve dma_mmu_remap[MAX_CMA_AREAS] __initdata;
> +static struct dma_contig_early_reserve dma_mmu_remap[MAX_EARLY_CMA_AREAS] __initdata;
>
> static int dma_mmu_remap_num __initdata;
>
> diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
> index f07168a0d3dd..f8f78f1434ea 100644
> --- a/arch/s390/mm/init.c
> +++ b/arch/s390/mm/init.c
> @@ -241,7 +241,7 @@ static int s390_cma_mem_notifier(struct notifier_block *nb,
> mem_data.start = arg->start_pfn << PAGE_SHIFT;
> mem_data.end = mem_data.start + (arg->nr_pages << PAGE_SHIFT);
> if (action == MEM_GOING_OFFLINE)
> - rc = cma_for_each_area(s390_cma_check_range, &mem_data);
> + rc = cma_for_each_early_area(s390_cma_check_range, &mem_data);
> return notifier_from_errno(rc);
> }
>
> diff --git a/include/linux/cma.h b/include/linux/cma.h
> index 8555d38a97b1..fb7a4923c3ba 100644
> --- a/include/linux/cma.h
> +++ b/include/linux/cma.h
> @@ -7,7 +7,7 @@
> #include <linux/numa.h>
>
> #ifdef CONFIG_CMA_AREAS
> -#define MAX_CMA_AREAS CONFIG_CMA_AREAS
> +#define MAX_EARLY_CMA_AREAS CONFIG_CMA_AREAS
> #endif
>
> #define CMA_MAX_NAME 64
> @@ -57,8 +57,14 @@ struct page *cma_alloc_frozen_compound(struct cma *cma, unsigned int order);
> bool cma_release_frozen(struct cma *cma, const struct page *pages,
> unsigned long count);
>
> +extern int cma_for_each_early_area(int (*it)(struct cma *cma, void *data), void *data);
> extern int cma_for_each_area(int (*it)(struct cma *cma, void *data), void *data);
> extern bool cma_intersects(struct cma *cma, unsigned long start, unsigned long end);
>
> extern void cma_reserve_pages_on_error(struct cma *cma);
> +
> +extern struct cma *cma_create(phys_addr_t base, phys_addr_t size,
> + unsigned int order_per_bit, const char *name);
> +extern void cma_free(struct cma *cma);
> +
> #endif
> diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c
> index f754079a287d..7975551f69b3 100644
> --- a/kernel/dma/contiguous.c
> +++ b/kernel/dma/contiguous.c
> @@ -52,7 +52,7 @@
> #define CMA_SIZE_MBYTES 0
> #endif
>
> -static struct cma *dma_contiguous_areas[MAX_CMA_AREAS];
> +static struct cma *dma_contiguous_areas[MAX_EARLY_CMA_AREAS];
> static unsigned int dma_contiguous_areas_num;
>
> static int dma_contiguous_insert_area(struct cma *cma)
> diff --git a/mm/cma.c b/mm/cma.c
> index a13ce4999b39..f989e2e98594 100644
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -34,7 +34,12 @@
> #include "internal.h"
> #include "cma.h"
>
> -struct cma cma_areas[MAX_CMA_AREAS];
> +static DEFINE_MUTEX(cma_lock);
> +
> +struct cma cma_early_areas[MAX_EARLY_CMA_AREAS];
> +unsigned int cma_early_area_count;
> +
> +static LIST_HEAD(cma_areas);
> unsigned int cma_area_count;
>
> phys_addr_t cma_get_base(const struct cma *cma)
> @@ -198,7 +203,6 @@ static void __init cma_activate_area(struct cma *cma)
> free_reserved_page(pfn_to_page(pfn));
> }
> }
> - totalcma_pages -= cma->count;
> cma->available_count = cma->count = 0;
> pr_err("CMA area %s could not be activated\n", cma->name);
> }
> @@ -207,8 +211,8 @@ static int __init cma_init_reserved_areas(void)
> {
> int i;
>
> - for (i = 0; i < cma_area_count; i++)
> - cma_activate_area(&cma_areas[i]);
> + for (i = 0; i < cma_early_area_count; i++)
> + cma_activate_area(&cma_early_areas[i]);
>
> return 0;
> }
> @@ -219,41 +223,77 @@ void __init cma_reserve_pages_on_error(struct cma *cma)
> set_bit(CMA_RESERVE_PAGES_ON_ERROR, &cma->flags);
> }
>
> +static void __init cma_init_area(struct cma *cma, const char *name,
> + phys_addr_t size, unsigned int order_per_bit)
> +{
> + if (name)
> + strscpy(cma->name, name);
> + else
> + snprintf(cma->name, CMA_MAX_NAME, "cma%d\n", cma_area_count);
> +
> + cma->available_count = cma->count = size >> PAGE_SHIFT;
> + cma->order_per_bit = order_per_bit;
> +
> + INIT_LIST_HEAD(&cma->node);
> +}
> +
> static int __init cma_new_area(const char *name, phys_addr_t size,
> unsigned int order_per_bit,
> struct cma **res_cma)
> {
> struct cma *cma;
>
> - if (cma_area_count == ARRAY_SIZE(cma_areas)) {
> + if (cma_early_area_count == ARRAY_SIZE(cma_early_areas)) {
> pr_err("Not enough slots for CMA reserved regions!\n");
> return -ENOSPC;
> }
>
> + mutex_lock(&cma_lock);
> +
> /*
> * Each reserved area must be initialised later, when more kernel
> * subsystems (like slab allocator) are available.
> */
> - cma = &cma_areas[cma_area_count];
> - cma_area_count++;
> + cma = &cma_early_areas[cma_early_area_count];
> + cma_early_area_count++;
>
> - if (name)
> - strscpy(cma->name, name);
> - else
> - snprintf(cma->name, CMA_MAX_NAME, "cma%d\n", cma_area_count);
> + cma_init_area(cma, name, size, order_per_bit);
>
> - cma->available_count = cma->count = size >> PAGE_SHIFT;
> - cma->order_per_bit = order_per_bit;
> - *res_cma = cma;
> totalcma_pages += cma->count;
> + *res_cma = cma;
> +
> + mutex_unlock(&cma_lock);
>
> return 0;
> }
>
> static void __init cma_drop_area(struct cma *cma)
> {
> + mutex_lock(&cma_lock);
> totalcma_pages -= cma->count;
> - cma_area_count--;
> + cma_early_area_count--;
> + mutex_unlock(&cma_lock);
> +}
> +
> +static int __init cma_check_memory(phys_addr_t base, phys_addr_t size)
> +{
> + if (!size || !memblock_is_region_reserved(base, size))
> + return -EINVAL;
> +
> + /*
> + * CMA uses CMA_MIN_ALIGNMENT_BYTES as alignment requirement which
> + * needs pageblock_order to be initialized. Let's enforce it.
> + */
> + if (!pageblock_order) {
> + pr_err("pageblock_order not yet initialized. Called during early boot?\n");
> + return -EINVAL;
> + }
> +
> + /* ensure minimal alignment required by mm core */
> + if (!IS_ALIGNED(base | size, CMA_MIN_ALIGNMENT_BYTES))
> + return -EINVAL;
> +
> + return 0;
> }
>
> /**
> @@ -276,22 +316,9 @@ int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size,
> struct cma *cma;
> int ret;
>
> - /* Sanity checks */
> - if (!size || !memblock_is_region_reserved(base, size))
> - return -EINVAL;
> -
> - /*
> - * CMA uses CMA_MIN_ALIGNMENT_BYTES as alignment requirement which
> - * needs pageblock_order to be initialized. Let's enforce it.
> - */
> - if (!pageblock_order) {
> - pr_err("pageblock_order not yet initialized. Called during early boot?\n");
> - return -EINVAL;
> - }
> -
> - /* ensure minimal alignment required by mm core */
> - if (!IS_ALIGNED(base | size, CMA_MIN_ALIGNMENT_BYTES))
> - return -EINVAL;
> + ret = cma_check_memory(base, size);
> + if (ret < 0)
> + return ret;
>
> ret = cma_new_area(name, size, order_per_bit, &cma);
> if (ret != 0)
> @@ -444,7 +471,7 @@ static int __init __cma_declare_contiguous_nid(phys_addr_t *basep,
> pr_debug("%s(size %pa, base %pa, limit %pa alignment %pa)\n",
> __func__, &size, &base, &limit, &alignment);
>
> - if (cma_area_count == ARRAY_SIZE(cma_areas)) {
> + if (cma_early_area_count == ARRAY_SIZE(cma_early_areas)) {
> pr_err("Not enough slots for CMA reserved regions!\n");
> return -ENOSPC;
> }
> @@ -1051,12 +1078,12 @@ bool cma_release_frozen(struct cma *cma, const struct page *pages,
> return true;
> }
>
> -int cma_for_each_area(int (*it)(struct cma *cma, void *data), void *data)
> +int cma_for_each_early_area(int (*it)(struct cma *cma, void *data), void *data)
> {
> int i;
>
> - for (i = 0; i < cma_area_count; i++) {
> - int ret = it(&cma_areas[i], data);
> + for (i = 0; i < cma_early_area_count; i++) {
> + int ret = it(&cma_early_areas[i], data);
>
> if (ret)
> return ret;
> @@ -1065,6 +1092,25 @@ int cma_for_each_area(int (*it)(struct cma *cma, void *data), void *data)
> return 0;
> }
>
> +int cma_for_each_area(int (*it)(struct cma *cma, void *data), void *data)
> +{
> + struct cma *cma;
> +
> + mutex_lock(&cma_lock);
> +
> + list_for_each_entry(cma, &cma_areas, node) {
> + int ret = it(cma, data);
> +
> + if (ret) {
> + mutex_unlock(&cma_lock);
> + return ret;
> + }
> + }
> +
> + mutex_unlock(&cma_lock);
> + return 0;
> +}
> +
> bool cma_intersects(struct cma *cma, unsigned long start, unsigned long end)
> {
> int r;
> @@ -1147,3 +1193,74 @@ void __init *cma_reserve_early(struct cma *cma, unsigned long size)
>
> return ret;
> }
> +
> +struct cma *__init cma_create(phys_addr_t base, phys_addr_t size,
> + unsigned int order_per_bit, const char *name)
> +{
> + struct cma *cma;
> + int ret;
> +
> + ret = cma_check_memory(base, size);
> + if (ret < 0)
> + return ERR_PTR(ret);
> +
> + cma = kzalloc_obj(*cma, GFP_KERNEL);
> + if (!cma)
> + return ERR_PTR(-ENOMEM);
> +
> + cma_init_area(cma, name, size, order_per_bit);
> + cma->ranges[0].base_pfn = PFN_DOWN(base);
> + cma->ranges[0].early_pfn = PFN_DOWN(base);
> + cma->ranges[0].count = cma->count;
> + cma->nranges = 1;
> +
> + cma_activate_area(cma);
> +
> + mutex_lock(&cma_lock);
> + list_add_tail(&cma->node, &cma_areas);
> + totalcma_pages += cma->count;
> + cma_area_count++;
> + mutex_unlock(&cma_lock);
> +
> + return cma;
> +}
> +
> +void cma_free(struct cma *cma)
> +{
> + unsigned int i;
> +
> + /*
> + * Safety check to prevent a CMA with active allocations from being
> + * released.
> + */
> + for (i = 0; i < cma->nranges; i++) {
> + unsigned long nbits = cma_bitmap_maxno(cma, &cma->ranges[i]);
> +
> + if (!bitmap_empty(cma->ranges[i].bitmap, nbits)) {
> + WARN(1, "%s: range %u not empty\n", cma->name, i);
> + return;
> + }
> + }
> +
> + /* free reserved pages and the bitmap */
> + for (i = 0; i < cma->nranges; i++) {
> + struct cma_memrange *cmr = &cma->ranges[i];
> + unsigned long end_pfn, pfn;
> +
> + end_pfn = cmr->base_pfn + cmr->count;
> + for (pfn = cmr->base_pfn; pfn < end_pfn; pfn++)
> + free_reserved_page(pfn_to_page(pfn));
> +
> + bitmap_free(cmr->bitmap);
> + }
> +
> + mutex_destroy(&cma->alloc_mutex);
> +
> + mutex_lock(&cma_lock);
> + totalcma_pages -= cma->count;
> + list_del(&cma->node);
> + cma_area_count--;
> + mutex_unlock(&cma_lock);
> +
> + kfree(cma);
> +}
> diff --git a/mm/cma.h b/mm/cma.h
> index c70180c36559..ae4db9819e38 100644
> --- a/mm/cma.h
> +++ b/mm/cma.h
> @@ -41,6 +41,7 @@ struct cma {
> unsigned long available_count;
> unsigned int order_per_bit; /* Order of pages represented by one bit */
> spinlock_t lock;
> + struct list_head node;
> struct mutex alloc_mutex;
> #ifdef CONFIG_CMA_DEBUGFS
> struct hlist_head mem_head;
> @@ -71,8 +72,8 @@ enum cma_flags {
> CMA_ACTIVATED,
> };
>
> -extern struct cma cma_areas[MAX_CMA_AREAS];
> -extern unsigned int cma_area_count;
> +extern struct cma cma_early_areas[MAX_EARLY_CMA_AREAS];
> +extern unsigned int cma_early_area_count;
>
> static inline unsigned long cma_bitmap_maxno(struct cma *cma,
> struct cma_memrange *cmr)
>
> --
> 2.54.0
>
^ permalink raw reply
* Re: [BUG] tracing: Too many tries to read user space
From: Masami Hiramatsu @ 2026-07-09 0:04 UTC (permalink / raw)
To: Steven Rostedt
Cc: Jeongho Choi, linux-trace-kernel, linux-kernel, mhiramat,
ji2yoon.jo, minki.jang, hajun.sung
In-Reply-To: <20260708091804.584975f9@gandalf.local.home>
On Wed, 8 Jul 2026 09:18:04 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:
> On Wed, 8 Jul 2026 21:37:53 +0900
> Jeongho Choi <jh1012.choi@samsung.com> wrote:
>
> > The code at the WARN location mentioned in the log above is as follows.
> >
> > 7374 if (WARN_ONCE(trys++ > 100, "Error: Too many
> > tries to read user space"))
> > 7375 return NULL;
> >
>
> This happens when something forces a schedule.
>
> >
> > Our current analysis is as follows:
> >
> > In the Gmail process, during a low memory situation, LMKD writes strings
> > to /sys/kernel/tracing/trace_marker for systrace recording. At the same
> > time, it broadcasts a sigkill due to low memory, which is causing the
> > LMKD trace marker operation to stall.
> >
>
> Can you see what is being scheduled in? Perhaps use the persistent ring
> buffer (if you can) and enable sched_switch tracepoint in it.
Nit: If the device just caused oom and not crash/reboot the kernel, you can
just use normal ring buffer (or perfetto).
Thanks,
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
^ permalink raw reply
* Re: [PATCH 15/30] mm: introduce and use linear_page_delta()
From: Ackerley Tng @ 2026-07-09 0:06 UTC (permalink / raw)
To: Lorenzo Stoakes, Andrew Morton
Cc: Russell King, Dinh Nguyen, Simon Schuster,
James E . J . Bottomley, Helge Deller, Jarkko Sakkinen,
Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Ian Abbott, H Hartley Sweeten, Lucas Stach, David Airlie,
Simona Vetter, Patrik Jakobsson, Maarten Lankhorst, Maxime Ripard,
Thomas Zimmermann, Rob Clark, Dmitry Baryshkov, Tomi Valkeinen,
Thierry Reding, Mikko Perttunen, Jonathan Hunter,
Christian Koenig, Huang Rui, Ankit Agrawal, Alex Williamson,
Alexander Viro, Christian Brauner, Dan Williams, Muchun Song,
Oscar Salvador, David Hildenbrand, Suren Baghdasaryan,
Liam R . Howlett, Matthew Wilcox, Marek Szyprowski,
Peter Zijlstra, Arnaldo Carvalho de Melo, Namhyung Kim,
Masami Hiramatsu, Oleg Nesterov, Steven Rostedt, SeongJae Park,
Miaohe Lin, Hugh Dickins, Mike Rapoport, Kees Cook, Paolo Bonzini,
linux-kernel, linux-arm-kernel, linux-parisc, linux-sgx, etnaviv,
dri-devel, linux-arm-msm, freedreno, linux-tegra, kvm,
linux-fsdevel, nvdimm, linux-mm, iommu, linux-perf-users,
linux-trace-kernel, kasan-dev, damon, Pedro Falcato, Rik van Riel,
Harry Yoo, Jann Horn
In-Reply-To: <eedf589778aaab33e6df2ad6556dcde536e13460.1782735110.git.ljs@kernel.org>
Lorenzo Stoakes <ljs@kernel.org> writes:
> It's often useful to obtain the number of pages a given address lies at
> within a VMA.
>
> Add linear_page_delta() to determine this and update linear_page_index() to
> make use of it.
>
> Add comments to describe both linear_page_delta() and linear_page_index().
>
> No functional change intended.
>
> Signed-off-by: Lorenzo Stoakes <ljs@kernel.org>
Reviewed-by: Ackerley Tng <ackerleytng@google.com>
>
> [...snip...]
>
^ permalink raw reply
* Re: [PATCH 19/30] mm: use linear_page_[index, delta]() consistently
From: Ackerley Tng @ 2026-07-09 0:06 UTC (permalink / raw)
To: Lorenzo Stoakes, Andrew Morton
Cc: Russell King, Dinh Nguyen, Simon Schuster,
James E . J . Bottomley, Helge Deller, Jarkko Sakkinen,
Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, x86,
Ian Abbott, H Hartley Sweeten, Lucas Stach, David Airlie,
Simona Vetter, Patrik Jakobsson, Maarten Lankhorst, Maxime Ripard,
Thomas Zimmermann, Rob Clark, Dmitry Baryshkov, Tomi Valkeinen,
Thierry Reding, Mikko Perttunen, Jonathan Hunter,
Christian Koenig, Huang Rui, Ankit Agrawal, Alex Williamson,
Alexander Viro, Christian Brauner, Dan Williams, Muchun Song,
Oscar Salvador, David Hildenbrand, Suren Baghdasaryan,
Liam R . Howlett, Matthew Wilcox, Marek Szyprowski,
Peter Zijlstra, Arnaldo Carvalho de Melo, Namhyung Kim,
Masami Hiramatsu, Oleg Nesterov, Steven Rostedt, SeongJae Park,
Miaohe Lin, Hugh Dickins, Mike Rapoport, Kees Cook, Paolo Bonzini,
linux-kernel, linux-arm-kernel, linux-parisc, linux-sgx, etnaviv,
dri-devel, linux-arm-msm, freedreno, linux-tegra, kvm,
linux-fsdevel, nvdimm, linux-mm, iommu, linux-perf-users,
linux-trace-kernel, kasan-dev, damon, Pedro Falcato, Rik van Riel,
Harry Yoo, Jann Horn
In-Reply-To: <bf56e2e98b512962a2fb88900d535a0e9e6769d8.1782735110.git.ljs@kernel.org>
Lorenzo Stoakes <ljs@kernel.org> writes:
> diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c
> index db57c5766ab6..f0e5da490866 100644
> --- a/virt/kvm/guest_memfd.c
> +++ b/virt/kvm/guest_memfd.c
> @@ -440,7 +440,7 @@ static int kvm_gmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpo
> static struct mempolicy *kvm_gmem_get_policy(struct vm_area_struct *vma,
> unsigned long addr, pgoff_t *ilx)
> {
> - pgoff_t pgoff = vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT);
> + pgoff_t pgoff = linear_page_index(vma, addr);
> struct inode *inode = file_inode(vma->vm_file);
>
> *ilx = inode->i_ino;
> --
> 2.54.0
For the guest_memfd change:
Reviewed-by: Ackerley Tng <ackerleytng@google.com>
Thank you!
^ permalink raw reply
* Re: [PATCH v10 5/6] Documentation: document panic_on_unrecoverable_memory_failure sysctl
From: Miaohe Lin @ 2026-07-09 3:18 UTC (permalink / raw)
To: Breno Leitao
Cc: linux-mm, linux-kernel, linux-doc, linux-kselftest,
linux-trace-kernel, kernel-team, Andrew Morton, David Hildenbrand,
Lorenzo Stoakes, Vlastimil Babka, Mike Rapoport,
Suren Baghdasaryan, Michal Hocko, Shuah Khan, Naoya Horiguchi,
Jonathan Corbet, Shuah Khan, Liam R. Howlett, lance.yang,
Steven Rostedt, Masami Hiramatsu, Mathieu Desnoyers
In-Reply-To: <20260630-ecc_panic-v10-5-c6ed5b62eea2@debian.org>
On 2026/6/30 20:46, Breno Leitao wrote:
> Add documentation for the new vm.panic_on_unrecoverable_memory_failure
> sysctl, describing which failures trigger a panic (kernel-owned pages
> the handler cannot recover) and which are intentionally left out
> (transient allocator races and unclassified pages).
>
> Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Miaohe Lin <linmiaohe@huawei.com>
Thanks.
.
^ permalink raw reply
* Re: [PATCH v2 1/4] mm/migrate: do not migrate folios mapped into VM_LOCKED VMAs under compaction
From: Wandun @ 2026-07-09 3:31 UTC (permalink / raw)
To: Lorenzo Stoakes
Cc: vbabka, david, rostedt, mhiramat, Alexander.Krabler, hughd, fvdl,
bigeasy, linux-mm, linux-kernel, linux-trace-kernel,
linux-rt-devel, akpm, surenb, mhocko, jackmanb, hannes, ziy, riel,
liam, harry, jannh, lance.yang, mathieu.desnoyers, matthew.brost,
joshua.hahnjy, rakie.kim, byungchul, gourry, ying.huang, apopple,
pfalcato
In-Reply-To: <akz7ythMxfIZeT0d@lucifer>
On 7/7/26 21:44, Lorenzo Stoakes wrote:
> (Being really nitty, your subject line is too long)
>
> Please don't reference legacy VMA flags for newer patches 'do not migrate
> folios mapped into mlocked VMAs...' works just as well.
Got it.
>
> On Tue, Jul 07, 2026 at 08:59:22PM +0800, Wandun Chen wrote:
>> From: Wandun Chen <chenwandun@lixiang.com>
>>
>> When compact_unevictable_allowed=0, unevictable pages should not be
>> migrated. However, mlock_folio_batch in the mlock[all] syscall introduces
>> a race, mlock_folio() sets PG_mlocked immediately but defers PG_unevictable
>> to mlock_folio_batch(), causing pages that are about to become unevictable
>> to be migrated, which violates the intent of compact_unevictable_allowed,
>> and causes spike latency in RT kernels [1].
>>
>> In order to fix this, migration is forbidden for pages mapped into VMAs
>> marked with VM_LOCKED. In addition, two early-return paths are introduced,
>
> Please don't reference legacy VMA flags. -> VMA_LOCKED_BIT.
Got it.
>
>> filter out mlocked pages, return early to avoid unnecessary operations.
>>
>> Fixes: 90d07210ab55 ("mm: mlock: use folios and a folio batch internally")
>
> Hmmmm why do you think my patch caused this? That was just a folio conversion?
Oh, I made a mistake, your patch was just a folio conversion.
Batching mlocked page was introduced in v5.18 by:
commit 2fbb0c10d1e8 ("mm/munlock: mlock_page() munlock_page() batch by pagevec")
Setting sysctl_compact_unevictable_allowed to zero was introduced in v5.7 by:
commit 6923aa0d8c62 ("mm/compaction: Disable compact_unevictable_allowed on RT")
So this issue exist after v5.18.
>
> Also I didn't think we liked having fixes spotted about a series with non-fixes
> tags?
Got it, will split this series in next version.
>
>> Reported-by: Alexander Krabler <Alexander.Krabler@kuka.com>
>> Closes: https://lore.kernel.org/all/DU0PR01MB10385345F7153F334100981888259A@DU0PR01MB10385.eurprd01.prod.exchangelabs.com/ [1]
>> Suggested-by: Vlastimil Babka <vbabka@suse.cz>
>> Signed-off-by: Wandun Chen <chenwandun@lixiang.com>
>> Link: https://lore.kernel.org/linux-rt-users/33275585-f2db-4779-89f0-3ae24b455a67@suse.cz/#t
>> ---
>> include/linux/compaction.h | 6 ++++++
>> include/linux/rmap.h | 3 +++
>> mm/compaction.c | 8 +++++++-
>> mm/migrate.c | 23 +++++++++++++++++++----
>> mm/rmap.c | 12 +++++++++---
>> 5 files changed, 44 insertions(+), 8 deletions(-)
>>
>> diff --git a/include/linux/compaction.h b/include/linux/compaction.h
>> index f29ef0653546..04e60f65b976 100644
>> --- a/include/linux/compaction.h
>> +++ b/include/linux/compaction.h
>> @@ -106,6 +106,7 @@ bool compaction_zonelist_suitable(struct alloc_context *ac, int order,
>> extern void __meminit kcompactd_run(int nid);
>> extern void __meminit kcompactd_stop(int nid);
>> extern void wakeup_kcompactd(pg_data_t *pgdat, int order, int highest_zoneidx);
>> +extern bool compaction_allow_unevictable(void);
>
> Don't use extern. We remove extern as we go it's not needed.
Got it.
>
>>
>> #else
>> static inline void reset_isolation_suitable(pg_data_t *pgdat)
>> @@ -131,6 +132,11 @@ static inline void wakeup_kcompactd(pg_data_t *pgdat,
>> {
>> }
>>
>> +static inline bool compaction_allow_unevictable(void)
>> +{
>> + return true;
>> +}
>> +
>> #endif /* CONFIG_COMPACTION */
>>
>> struct node;
>> diff --git a/include/linux/rmap.h b/include/linux/rmap.h
>> index 8dc0871e5f00..359c7426b6b9 100644
>> --- a/include/linux/rmap.h
>> +++ b/include/linux/rmap.h
>> @@ -102,6 +102,9 @@ enum ttu_flags {
>> * do a final flush if necessary */
>> TTU_RMAP_LOCKED = 0x80, /* do not grab rmap lock:
>> * caller holds it */
>> + TTU_RESPECT_MLOCK = 0x100,/* leave VM_LOCKED vmas mapped instead
>
> -> VMA_LOCKED_BIT please. Also maybe just say mlock'd?
Got it.
>
>> + * of installing a migration entry
>> + */
>> };
>>
>> #ifdef CONFIG_MMU
>> diff --git a/mm/compaction.c b/mm/compaction.c
>> index f08765ade014..5d256930e389 100644
>> --- a/mm/compaction.c
>> +++ b/mm/compaction.c
>> @@ -1116,7 +1116,8 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
>> is_unevictable = folio_test_unevictable(folio);
>>
>> /* Compaction might skip unevictable pages but CMA takes them */
>> - if (!(mode & ISOLATE_UNEVICTABLE) && is_unevictable)
>> + if (!(mode & ISOLATE_UNEVICTABLE) &&
>> + (is_unevictable || folio_test_mlocked(folio)))
>
> Maybe just change is_unevictable to include this check?
>
> Like:
>
> is_unevictable = folio_test_unevictable(folio) ||
> folio_test_mlocked(folio);
>
> ?
Sounds good, I'll fold mlock into is_unevictable so both checks
stay consistent.
>
> Also later you have:
>
> if (((mode & ISOLATE_ASYNC_MIGRATE) && is_dirty) ||
> (mapping && is_unevictable)) {
> ...
>
> Which doesn't account for mlock as-is? Is that correct?
IIUC, The is_unevictable check here mainly serves as a cheap pre-filter
for inaccessible mappings (which are always unevictable folio).
It's unrelated to the mlock.
>
>
>
>> goto isolate_fail_put;
>>
>> /*
>> @@ -1898,6 +1899,11 @@ typedef enum {
>> * compactable pages.
>> */
>> static int sysctl_compact_unevictable_allowed __read_mostly = CONFIG_COMPACT_UNEVICTABLE_DEFAULT;
>> +
>> +bool compaction_allow_unevictable(void)
>> +{
>> + return sysctl_compact_unevictable_allowed;
>> +}
>
> You add this helper but isolate_migratepages() still references
> sysctl_compact_unevictable_allowed directly?
I'll route that reference through compaction_allow_unevictable()
in next version.
>
>> /*
>> * Tunable for proactive compaction. It determines how
>> * aggressively the kernel should compact memory in the
>> diff --git a/mm/migrate.c b/mm/migrate.c
>> index a786549551e3..3a15eb13e82b 100644
>> --- a/mm/migrate.c
>> +++ b/mm/migrate.c
>> @@ -1202,7 +1202,7 @@ static void migrate_folio_done(struct folio *src,
>> static int migrate_folio_unmap(new_folio_t get_new_folio,
>> free_folio_t put_new_folio, unsigned long private,
>> struct folio *src, struct folio **dstp, enum migrate_mode mode,
>> - struct list_head *ret)
>> + struct list_head *ret, enum migrate_reason reason)
>> {
>> struct folio *dst;
>> int rc = -EAGAIN;
>> @@ -1210,6 +1210,7 @@ static int migrate_folio_unmap(new_folio_t get_new_folio,
>> struct anon_vma *anon_vma = NULL;
>> bool locked = false;
>> bool dst_locked = false;
>> + enum ttu_flags ttu = 0;
>
> You reference ttu only in an if-block below no? So why are you declaring
> this here? Move it to the if-block.
Got it. I'll move it to the if-block in next version.
>
>>
>> dst = get_new_folio(src, private);
>> if (!dst)
>> @@ -1249,9 +1250,15 @@ static int migrate_folio_unmap(new_folio_t get_new_folio,
>> folio_lock(src);
>> }
>> locked = true;
>> - if (folio_test_mlocked(src))
>> + if (folio_test_mlocked(src)) {
>> old_folio_state |= FOLIO_WAS_MLOCKED;
>>
>> + if (reason == MR_COMPACTION && !compaction_allow_unevictable()) {
>
> This should really be a helper since you repeat yourself and it's not
> obvious what this is checking.
>
> Like:
>
> static migrate_mlock_allowed(enum migrate_reason reason)
> {
> /* Only compaction is disallowed. */
> if (reason != MR_COMPACTION)
> return true;
>
> /* If we can compact unevictable folios, we are ok. */
> if (compaction_allow_unevictable())
> return true;
>
> /* Conservative: if any folio could be mlock()'d, disallow. */
> return false;
> }
>
> Then you could self-document what you're checking and avoid code duplication below.
Got it, it is more clear, thanks.
>
>> + rc = -EBUSY;
>> + goto out;
>> + }
>> + }
>> +
>> if (folio_test_writeback(src)) {
>> /*
>> * Only in the case of a full synchronous migration is it
>> @@ -1324,7 +1331,14 @@ static int migrate_folio_unmap(new_folio_t get_new_folio,
>> /* Establish migration ptes */
>> VM_BUG_ON_FOLIO(folio_test_anon(src) &&
>> !folio_test_ksm(src) && !anon_vma, src);
>
> Useful to convert VM_BUG_*() -> VM_WARN_*() (possibly _ONCE() here also) as we go!
Got it.
>
>> - try_to_migrate(src, mode == MIGRATE_ASYNC ? TTU_BATCH_FLUSH : 0);
>> +
>> + if (mode == MIGRATE_ASYNC)
>> + ttu |= TTU_BATCH_FLUSH;
>> +
>> + if (reason == MR_COMPACTION && !compaction_allow_unevictable())
>
> See above about deduplicating.
>
>> + ttu |= TTU_RESPECT_MLOCK;
>
> Hmm. I don't love 'respect mlock'. I guess we only know about the reason
> being compaction here.
Right, we only know about the reason.
>
> But I'm confused anyway. We have the folio, why aren't we just checking for
> PG_mlocked() here instead of getting the rmap to see if it's mapped
> anywhere with VMA_LOCKED_BIT?
There was a race scenario without patch 02, vma may already marked with
VMA_LOCKED_BIT but folio has't marked with mlocked, such as below:
CPUA: mlock() CPUB: compaction / migration
mmap_write_lock()
mlock_fixup set VM_CLOKED
mlock_pte_range
mlock_folio(page N)
isolate page N+50 (mlock hasn't reached it)
migrate_folio_unmap
folio_test_mlocked() --> false, but VMA:VM_LOCKED
try_to_migrate()
rmap_walk(P) [anon_vma rwsem / i_mmap_rwsem, read]
try_to_migrate_one -->install migration entry
...reaches page N+50
skip migration entry (without patch 02)
mmap_write_unlock()
access page N + 50 --> wait for migration complete
migrate_folios_move
....
migrate complete
If apply patch 02, mlock itself will wait migration complete, so checking
VMA_LOCKED_BIT in the rmap path is no longer necessary, but this logic is
retained to avoid unnecessary migration operations.
>
>> +
>> + try_to_migrate(src, ttu);
>> old_folio_state |= FOLIO_WAS_MAPPED;
>> }
>>
>> @@ -1905,7 +1919,8 @@ static int migrate_pages_batch(struct list_head *from,
>> }
>>
>> rc = migrate_folio_unmap(get_new_folio, put_new_folio,
>> - private, folio, &dst, mode, ret_folios);
>> + private, folio, &dst, mode, ret_folios,
>> + reason);
>> /*
>> * The rules are:
>> * 0: folio will be put on unmap_folios list,
>> diff --git a/mm/rmap.c b/mm/rmap.c
>> index 0fb7a1b82cf3..3cb7f6337d38 100644
>> --- a/mm/rmap.c
>> +++ b/mm/rmap.c
>> @@ -2420,6 +2420,9 @@ static bool try_to_migrate_one(struct folio *folio, struct vm_area_struct *vma,
>> unsigned long pfn;
>> unsigned long hsz = 0;
>>
>> + if ((flags & TTU_RESPECT_MLOCK) && (vma->vm_flags & VM_LOCKED))
>
> Please use the modern API for VMA flags. So:
>
> if ((flags & TTU_RESPECT_MLOCK) && vma_test(VMA_LOCKED_BIT))
Got it.
>
>> + return false;
>> +
>> /*
>> * When racing against e.g. zap_pte_range() on another cpu,
>> * in between its ptep_get_and_clear_full() and folio_remove_rmap_*(),
>> @@ -2741,11 +2744,14 @@ void try_to_migrate(struct folio *folio, enum ttu_flags flags)
>> };
>>
>> /*
>> - * Migration always ignores mlock and only supports TTU_RMAP_LOCKED and
>> - * TTU_SPLIT_HUGE_PMD, TTU_SYNC, and TTU_BATCH_FLUSH flags.
>> + * Migration normally ignores mlock, but TTU_RESPECT_MLOCK asks it to
>> + * leave folios mapped into VM_LOCKED vmas alone. Only TTU_RMAP_LOCKED,
>
> Again -> VMA_LOCKED_BIT.
>
>> + * TTU_SPLIT_HUGE_PMD, TTU_SYNC, TTU_BATCH_FLUSH and TTU_RESPECT_MLOCK
>> + * are supported.
>> */
>> if (WARN_ON_ONCE(flags & ~(TTU_RMAP_LOCKED | TTU_SPLIT_HUGE_PMD |
>> - TTU_SYNC | TTU_BATCH_FLUSH)))
>> + TTU_SYNC | TTU_BATCH_FLUSH |
>> + TTU_RESPECT_MLOCK)))
>> return;
>>
>> if (folio_is_zone_device(folio) &&
>> --
>> 2.43.0
>>
>
> Thanks, Lorenzo
Thank you for the detailed review, Lorenzo.
many of the comments are very meaningful :)
Best regards
Wandun
^ permalink raw reply
* Re: [PATCH v10 6/6] selftests/mm: add hwpoison-panic destructive test
From: Miaohe Lin @ 2026-07-09 3:34 UTC (permalink / raw)
To: Breno Leitao
Cc: linux-mm, linux-kernel, linux-doc, linux-kselftest,
linux-trace-kernel, kernel-team, Andrew Morton, David Hildenbrand,
Lorenzo Stoakes, Vlastimil Babka, Mike Rapoport,
Suren Baghdasaryan, Michal Hocko, Shuah Khan, Naoya Horiguchi,
Jonathan Corbet, Shuah Khan, Liam R. Howlett, lance.yang,
Steven Rostedt, Masami Hiramatsu, Mathieu Desnoyers
In-Reply-To: <20260630-ecc_panic-v10-6-c6ed5b62eea2@debian.org>
On 2026/6/30 20:46, Breno Leitao wrote:
> Add a destructive selftest that verifies
> vm.panic_on_unrecoverable_memory_failure actually panics when a
> hwpoison error hits a kernel-owned page.
>
> Three "kinds" of kernel-owned page can be targeted, selectable via
> the script's first positional argument (default: rodata):
>
> rodata - a PG_reserved page in the kernel rodata range, sourced
> from the "Kernel rodata" sub-resource of "System RAM" in
> /proc/iomem. That entry is reported on every major
> architecture and guarantees the chosen PFN is backed by
> struct page (an online System RAM range, not a firmware
> hole), is PG_reserved, and is read-only -- so even if
> the panic fails to fire for some reason, the resulting
> PG_hwpoison marker on rodata does not corrupt writable
> kernel state.
>
> slab - a slab page found by walking /proc/kpageflags for the
> first PFN with KPF_SLAB set (and KPF_HWPOISON / KPF_NOPAGE
> / KPF_COMPOUND_TAIL clear). Exercises the get_any_page()
> path on a non PG_reserved kernel-owned page and so
> catches regressions where get_any_page() collapses
> kernel-owned pages into a transient -EIO instead of
> -ENOTRECOVERABLE.
>
> pgtable - same as slab, but the PFN is selected via KPF_PGTABLE.
>
> PageLargeKmalloc, the fourth page type matched by
> is_kernel_owned_page(), is intentionally not covered: it is a
> PAGE_TYPE_OPS flag with no /proc/kpageflags bit, so selecting such
> a PFN from userspace is not feasible. The slab and pgtable
> variants already exercise the same get_any_page() positive-check
> branch.
>
> The script enables the sysctl and writes the selected physical
> address to /sys/devices/system/memory/hard_offline_page. A
> successful run crashes the kernel with
>
> Memory failure: <pfn>: unrecoverable page
>
> A return from the inject means no panic fired. Before reporting, the
> script restores the sysctl and best-effort unpoisons the target PFN
> through the hwpoison debugfs interface (hard_offline_page() injects
> with MF_SW_SIMULATED, so the page stays unpoisonable), then re-reads
> /proc/kpageflags: a PFN that is still the kernel-owned type it selected
> is a genuine failure, while one that raced to a different type before
> the inject is skipped as inconclusive. Test outcome is therefore
> observed externally (serial console, kdump) rather than from the
> script's own exit code.
>
> The script is intentionally NOT wired into run_vmtests.sh: every
> successful run panics the kernel, which is incompatible with the
> sequential "run each category in the same VM" model that
> run_vmtests.sh assumes. It is also not registered as a TEST_PROGS /
> ksft_* wrapper so a default kselftest run does not opt itself into
> a panic. The script is meant to be executed manually inside a
> disposable VM (e.g. virtme-ng), one variant per VM boot, and
> requires RUN_DESTRUCTIVE=1 in the environment as a safety net.
>
> Signed-off-by: Breno Leitao <leitao@debian.org>
With Mike's comment addressed:
Acked-by: Miaohe Lin <linmiaohe@huawei.com>
Thanks.
.
^ permalink raw reply
* Re: [PATCH] selftests/tracing: Have trigger-hist-poll.tc use sched_process_exit
From: Masami Hiramatsu @ 2026-07-09 4:58 UTC (permalink / raw)
To: Steven Rostedt
Cc: LKML, Linux Trace Kernel, linux-kselftest, Masami Hiramatsu,
Mathieu Desnoyers, Shuah Khan, Shuah Khan
In-Reply-To: <20260708163731.566a86aa@gandalf.local.home>
On Wed, 8 Jul 2026 16:37:31 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:
> On Wed, 8 Jul 2026 16:35:39 -0400
> Steven Rostedt <rostedt@goodmis.org> wrote:
>
> > I forgot to mention that I tested this with and without CONFIG_RCU_LAZY.
> > With that config disabled, the test passes. With it enabled, it always
> > fails.
>
> And I also traced it with:
>
> trace-cmd set -p function_graph -l event_hist_poll -O funcgraph-retval
>
> and it shows the sched_process_free being called for the sleep process
> *after* the poll finishes.
Thanks for fix and tested!!
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
>
> -- Steve
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
^ permalink raw reply
* Re: [PATCH] selftests/ftrace: Fix reading enabled_functions in add_remove_fprobe_module test
From: Masami Hiramatsu @ 2026-07-09 5:38 UTC (permalink / raw)
To: Steven Rostedt
Cc: LKML, Linux Trace Kernel, linux-kselftest, Masami Hiramatsu,
Mathieu Desnoyers, Shuah Khan, Shuah Khan
In-Reply-To: <20260708153239.055d56dd@gandalf.local.home>
On Wed, 8 Jul 2026 15:32:39 -0400
Steven Rostedt <rostedt@goodmis.org> wrote:
> From: Steven Rostedt <rostedt@goodmis.org>
>
> The add_remove_fprobe_module test checks the number of functions added to
> the enabled_functions file to make sure that the functions added or
> removed is as expected. The issue is that it expects this file to be empty
> on start up.
>
> Now that systemd uses BPF that attaches to functions via ftrace, this file
> is not empty in several systems:
>
> # cat /sys/kernel/tracing/enabled_functions
> bpf_lsm_file_open (1) R D M tramp: ftrace_regs_caller+0x0/0x61 (call_direct_funcs+0x0/0x50)
> direct(jmp)-->bpf_trampoline_6442529439+0x0/0xe9
>
> Change the test to read the number of lines in enabled_functions at the
> start of the test and subtract that from the value of the count for the
> checks within the test.
Oops, good catch! I need to make a test environment which uses
systemd...
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Thanks,
>
> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
> ---
> .../dynevent/add_remove_fprobe_module.tc | 27 ++++++++++++-------
> 1 file changed, 18 insertions(+), 9 deletions(-)
>
> diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_module.tc b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_module.tc
> index 2915206777b6..89660a9adf44 100644
> --- a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_module.tc
> +++ b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_module.tc
> @@ -16,23 +16,32 @@ echo > dynamic_events
> FUNC1='foo_bar*'
> FUNC2='vfs_read'
>
> +:;: "Save enabled functions count" ;:
> +ecount=`cat enabled_functions | wc -l`
> +
> +count_enabled_functions() {
> + count=`cat enabled_functions | wc -l`
> + count=$(($count-$ecount))
> + echo $count
> +}
> +
> :;: "Add an event on the test module" ;:
> echo "f:test1 $FUNC1" >> dynamic_events
> echo 1 > events/fprobes/test1/enable
>
> :;: "Ensure it is enabled" ;:
> -funcs=`cat enabled_functions | wc -l`
> +funcs=`count_enabled_functions`
> test $funcs -ne 0
>
> :;: "Check the enabled_functions is cleared on unloading" ;:
> rmmod trace-events-sample
> -funcs=`cat enabled_functions | wc -l`
> +funcs=`count_enabled_functions`
> test $funcs -eq 0
>
> :;: "Check it is kept clean" ;:
> modprobe trace-events-sample
> echo 1 > events/fprobes/test1/enable || echo "OK"
> -funcs=`cat enabled_functions | wc -l`
> +funcs=`count_enabled_functions`
> test $funcs -eq 0
>
> :;: "Add another event not on the test module" ;:
> @@ -40,19 +49,19 @@ echo "f:test2 $FUNC2" >> dynamic_events
> echo 1 > events/fprobes/test2/enable
>
> :;: "Ensure it is enabled" ;:
> -ofuncs=`cat enabled_functions | wc -l`
> +ofuncs=`count_enabled_functions`
> test $ofuncs -ne 0
>
> :;: "Disable and remove the first event"
> echo 0 > events/fprobes/test1/enable
> echo "-:fprobes/test1" >> dynamic_events
> -funcs=`cat enabled_functions | wc -l`
> +funcs=`count_enabled_functions`
> test $ofuncs -eq $funcs
>
> :;: "Disable and remove other events" ;:
> echo 0 > events/fprobes/enable
> echo > dynamic_events
> -funcs=`cat enabled_functions | wc -l`
> +funcs=`count_enabled_functions`
> test $funcs -eq 0
>
> rmmod trace-events-sample
> @@ -63,12 +72,12 @@ echo "f:test1 $FUNC1" >> dynamic_events
> echo 1 > events/fprobes/test1/enable
> echo "f:test2 $FUNC2" >> dynamic_events
> echo 1 > events/fprobes/test2/enable
> -ofuncs=`cat enabled_functions | wc -l`
> +ofuncs=`count_enabled_functions`
> test $ofuncs -ne 0
>
> :;: "Unload module (ftrace entry should be removed)" ;:
> rmmod trace-events-sample
> -funcs=`cat enabled_functions | wc -l`
> +funcs=`count_enabled_functions`
> test $funcs -ne 0
> test $ofuncs -ne $funcs
>
> @@ -77,7 +86,7 @@ echo 0 > events/fprobes/test2/enable
> echo "-:fprobes/test2" >> dynamic_events
>
> :;: "Ensure ftrace is disabled." ;:
> -funcs=`cat enabled_functions | wc -l`
> +funcs=`count_enabled_functions`
> test $funcs -eq 0
>
> echo 0 > events/fprobes/enable
> --
> 2.53.0
>
--
Masami Hiramatsu (Google) <mhiramat@kernel.org>
^ permalink raw reply
* Re: [PATCH v3 06/11] mm/cma: Allow dynamically creating CMA areas
From: Marek Szyprowski @ 2026-07-09 5:56 UTC (permalink / raw)
To: David Hildenbrand (Arm), Thierry Reding, Rob Herring,
Krzysztof Kozlowski, Conor Dooley, Jonathan Hunter,
Mikko Perttunen, Yury Norov, Rasmus Villemoes, Russell King,
Alexander Gordeev, Gerald Schaefer, Heiko Carstens, Vasily Gorbik,
Christian Borntraeger, Sven Schnelle, Andrew Morton,
Lorenzo Stoakes, Liam R. Howlett, Vlastimil Babka, Mike Rapoport,
Suren Baghdasaryan, Michal Hocko, Robin Murphy, Sumit Semwal,
Benjamin Gaignard, Brian Starkey, John Stultz, T.J. Mercier,
Christian König, Steven Rostedt, Masami Hiramatsu,
Mathieu Desnoyers, Catalin Marinas, Will Deacon
Cc: devicetree, linux-tegra, linux-kernel, dri-devel, linux-media,
linux-arm-kernel, linux-s390, linux-mm, iommu, linaro-mm-sig,
linux-trace-kernel
In-Reply-To: <e212caac-6c30-448a-9e10-32fff8b842f6@kernel.org>
On 08.07.2026 10:35, David Hildenbrand (Arm) wrote:
> On 7/7/26 12:02, Marek Szyprowski wrote:
>> On 01.07.2026 18:08, Thierry Reding wrote:
>>> From: Thierry Reding <treding@nvidia.com>
>>>
>>> There is no technical reason why there should be a limited number of CMA
>>> regions, so extract some code into helpers and use them to create extra
>>> functions (cma_create() and cma_free()) that allow creating and freeing,
>>> respectively, CMA regions dynamically at runtime.
>>
>> Well, the technical reason for not creating cma regions dynamically at
>> runtime is that on some architectures (like 32bit ARM) the early fixup
>> for the region is needed to make it functional for DMA.
> Can you point me at the code that does that? Thanks!
Check dma_contiguous_early_fixup() and dma_contiguous_remap() in
arch/arm/mm/dma-mapping.c. Those functions ensures that the CPU mappings for
the CMA reserved region in linear map are remapped with 4k pages instead
of the 1M sections, so later, it will be possible to alter the mappings and
change them to coherent when needed (altering 1M sections is not possible,
because each process has it's own level-1 array even for the kernel linear
mapping).
However, in the use case in this patchset the reserved region is only shared
with buddy allocator by using the CMA infrastructure, not registered to the
regular DMA-mapping API, so it would work fine. I'm not convinced that this
is the right API to use for this though.
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
^ permalink raw reply
* Re: [PATCH v3 13/17] verification/rvgen: Add the rvgen kunit subcommand
From: Nam Cao @ 2026-07-09 8:02 UTC (permalink / raw)
To: Gabriele Monaco, linux-trace-kernel, linux-kernel, Steven Rostedt,
Gabriele Monaco
Cc: Thomas Weissschuh, Tomas Glozar, John Kacur, Wen Yang
In-Reply-To: <20260625121440.116317-14-gmonaco@redhat.com>
Gabriele Monaco <gmonaco@redhat.com> writes:
> + def print_files(self):
> +
> + handlers = self.__parse_attach_handlers()
> +
> + if not handlers:
> + print(f"No handlers found registered with rv_attach_trace_probe in {self.monitor_path}")
> + return
There is no valid monitor without any handler, right? If so, should we
throw an exception here?
> +
> + print("Found tracepoint handler(s):")
> + for handler in handlers:
> + print(f" - {handler}")
> +
> + prototypes = []
> + assignments = []
> + for handler in handlers:
> + arguments = self.__extract_function_args(handler)
> +
> + prototypes.append(f"void (*{handler})({arguments});")
> + assignments.append(f".{handler} = {handler},")
> +
> + struct_name = f"rv_{self.name}_ops"
> +
> + self.__fill_monitor_handlers(struct_name, assignments)
> +
> + dir_path = os.path.dirname(self.monitor_path)
> +
> + header_file_path = os.path.join(dir_path, f"{self.name}_kunit.h")
> + kunit_c_file_path = os.path.join(dir_path, f"{self.name}_kunit.c")
> +
> + use_backup = True
> + if os.path.exists(header_file_path) or os.path.exists(kunit_c_file_path):
> + try:
> + response = input("KUnit file(s) already exist. Overwrite? [y/N] (N for backup): ")
> + if response.strip().lower() in ("y", "yes"):
> + use_backup = False
> + except EOFError:
> + print("Non-interactive session detected, not overwriting existing files.")
> + else:
> + use_backup = False
> +
> + if use_backup:
> + header_file_path += ".bak"
> + kunit_c_file_path += ".bak"
This is the opposite of what other software do. Usually they copy the
original file to a different name (with a prefix or a suffix), and
overwrite the original file.
I think it's best to follow the usual practice to avoid confusion, maybe
something like this:
if os.path.exists(header_file_path) or os.path.exists(kunit_c_file_path):
try:
response = input("KUnit file(s) already exist. Backup? [Y/n]")
if not response.strip().lower() in ("n", "no"):
...rename the file...
except EOFError:
print("Non-interactive session detected, not overwriting existing files.")
Nam
^ permalink raw reply
* Re: [PATCH v3 14/17] verification/rvgen: Add selftests for rvgen kunit
From: Nam Cao @ 2026-07-09 8:11 UTC (permalink / raw)
To: Gabriele Monaco, linux-trace-kernel, linux-kernel, Steven Rostedt,
Gabriele Monaco
Cc: Thomas Weissschuh, Tomas Glozar, John Kacur, Wen Yang
In-Reply-To: <20260625121440.116317-15-gmonaco@redhat.com>
Gabriele Monaco <gmonaco@redhat.com> writes:
> The rvgen kunit command patches monitor files and adds necessary
> definitions for kunit tests.
>
> Add a test case validating its behaviour on dummy generated files and
> comparing it against reference files, like it's done for rvgen monitor.
>
> Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
I am not entirely sure about this. In the future, when the generation
output is changed, all the references files also need to be updated. So
it's not clear to me if this really saves future development effort.
But well, we will see. For now:
Reviewed-by: Nam Cao <namcao@linutronix.de>
^ permalink raw reply
* Re: [PATCH v3 15/17] selftests/verification: Fix wrong errexit assumption
From: Nam Cao @ 2026-07-09 8:14 UTC (permalink / raw)
To: Gabriele Monaco, linux-trace-kernel, linux-kernel, Steven Rostedt,
Gabriele Monaco, Shuah Khan, linux-kselftest
Cc: Thomas Weissschuh, Tomas Glozar, John Kacur, Wen Yang
In-Reply-To: <20260625121440.116317-16-gmonaco@redhat.com>
Gabriele Monaco <gmonaco@redhat.com> writes:
> RV selftest rely on bash errexit (set -e) to terminate with error, when
> a step is expected to return false, the following syntax is used:
>
> ! cmd
>
> This however prevents the test from exiting when cmd is false (desired)
> but doesn't exit if cmd is true, since commands prefixed with ! are
> explicitly excluded from errexit.
>
> Use the syntax
>
> ! cmd || false
>
> Which ends up checking the exit value of ! cmd and supplies a false
> command for errexit to evaluate.
>
> Signed-off-by: Gabriele Monaco <gmonaco@redhat.com>
Sounds reasonable.
Acked-by: Nam Cao <namcao@linutronix.de>
^ permalink raw reply
* Re: [PATCH v2 1/4] mm/migrate: do not migrate folios mapped into VM_LOCKED VMAs under compaction
From: Wandun @ 2026-07-09 8:25 UTC (permalink / raw)
To: Lorenzo Stoakes
Cc: vbabka, david, rostedt, mhiramat, Alexander.Krabler, hughd, fvdl,
bigeasy, linux-mm, linux-kernel, linux-trace-kernel,
linux-rt-devel, akpm, surenb, mhocko, jackmanb, hannes, ziy, riel,
liam, harry, jannh, lance.yang, mathieu.desnoyers, matthew.brost,
joshua.hahnjy, rakie.kim, byungchul, gourry, ying.huang, apopple,
pfalcato
In-Reply-To: <ak0EsCeucJarlI7G@lucifer>
On 7/7/26 21:55, Lorenzo Stoakes wrote:
> On Tue, Jul 07, 2026 at 02:44:50PM +0100, Lorenzo Stoakes wrote:
>> See above about deduplicating.
>>
>>> + ttu |= TTU_RESPECT_MLOCK;
>>
>> Hmm. I don't love 'respect mlock'. I guess we only know about the reason
>> being compaction here.
>>
>> But I'm confused anyway. We have the folio, why aren't we just checking for
>> PG_mlocked() here instead of getting the rmap to see if it's mapped
>> anywhere with VMA_LOCKED_BIT?
>
> Also, since compaction_allow_unevictable() is a function that is accessible
> elsewhere, you could literally just have a TTU_MIGRATION here instead and have
> the rmap logic call compaction_allow_unevictable() instead rather than this.
Do you mean:
1. change TTU_RESPECT_MLOCK to TTU_MIGRATION, that'is OK.
2. move call compaction_allow_unevictable() to try_to_migrate_one? but as you suggested
migrate_mlock_allowed function, it already called compaction_allow_unevictable()
in order to determine whether TTU_MIGRATION needs to be added. Did I misunderstand
something somewhere?
>
> And then you could adapt the function I suggested before not to take a reason
> parameter but rather a 'is_migration' one instead possibly and then pass (ttu &
> TTU_MIGRATION) in.
>
> BUT. I still question whether this is at all needed since you have the folio you
> can check for PG_mlocked...
I described a race scenario at this link:
https://lore.kernel.org/lkml/c372e68f-2bfc-45b6-a431-01bf55717247@gmail.com/
>
> Cheers, Lorenzo
^ permalink raw reply
* Re: [PATCH v2 2/4] mm/mlock: wait for migration to finish when mlocking a folio
From: Sebastian Andrzej Siewior @ 2026-07-09 8:42 UTC (permalink / raw)
To: Lorenzo Stoakes
Cc: Wandun Chen, vbabka, david, rostedt, mhiramat, Alexander.Krabler,
hughd, fvdl, linux-mm, linux-kernel, linux-trace-kernel,
linux-rt-devel, akpm, surenb, mhocko, jackmanb, hannes, ziy, riel,
liam, harry, jannh, lance.yang, mathieu.desnoyers, matthew.brost,
joshua.hahnjy, rakie.kim, byungchul, gourry, ying.huang, apopple,
pfalcato
In-Reply-To: <ak0C-DP_1ZrTVSLj@lucifer>
On 2026-07-07 15:33:32 [+0100], Lorenzo Stoakes wrote:
> On Tue, Jul 07, 2026 at 08:59:23PM +0800, Wandun Chen wrote:
> > From: Wandun Chen <chenwandun@lixiang.com>
> >
> > In RT kernels, sysctl_compact_unevictable_allowed is false by default,
> > when the mlock/mlockall system call try to lock all the present page,
> > the mlock_pte_range function skips non-present entries. If these
> > non-present entries are migration entries, and the migration is not
> > guaranteed to have completed before the mlock/mlockall, it may result
> > in a page fault on subsequent access, which then waits for the
> > migration to finish, causing spike latency in RT kernels.
>
> Is this really noticable and measurable?
You want to avoid page faults like this which is why you do mlock in the
first place.
If the thread has a RT priority and it blocks here then other RT threads
will be scheduled and your migration thread, which will resolve this, is
SCHED_OTHER and the last one in the line. Assuming that thread has a 1ms
cycle/ deadline then it will likely miss it.
> I suppose not too many ranges should be mock
Sebastian
^ permalink raw reply
* Re: [PATCH v2 4/4] mm/mlock: migrate folios out of CMA when mlocking a range
From: Sebastian Andrzej Siewior @ 2026-07-09 9:13 UTC (permalink / raw)
To: Lorenzo Stoakes
Cc: Wandun Chen, vbabka, david, rostedt, mhiramat, Alexander.Krabler,
hughd, fvdl, linux-mm, linux-kernel, linux-trace-kernel,
linux-rt-devel, akpm, surenb, mhocko, jackmanb, hannes, ziy, riel,
liam, harry, jannh, lance.yang, mathieu.desnoyers, matthew.brost,
joshua.hahnjy, rakie.kim, byungchul, gourry, ying.huang, apopple,
pfalcato
In-Reply-To: <ak0OZKzapUefmA3v@lucifer>
On 2026-07-07 15:54:57 [+0100], Lorenzo Stoakes wrote:
> On Tue, Jul 07, 2026 at 08:59:25PM +0800, Wandun Chen wrote:
> > From: Wandun Chen <chenwandun@lixiang.com>
> >
> > The region covered by mlock[all] may contain CMA pages. cma_alloc installs
> > migration entries in the page table, if a memory access occurs at this
> > point, it must wait for the migration to complete, which may cause
> > latency spikes on the RT kernels.
> >
> > Try to move the migration cost into the mlock[all] caller, which is
> > typically a setup path. So reduce the chance of latency spikes on RT
> > kernels by migrating the currently mapped CMA pages out of CMA region.
>
> 'reduce the chances of latency' so do you have any data to back this invasive
> change or not?
The application gets pages assigned which belong a CMA area. If the
pages are in need by the CMA then those pages are replaced with other
pages during a migration phase. Since there is no guarantee how long
this will take and is also subject to general scheduling in the system
it will be measurable and painful once hit.
> And for RT, but nothing in here at all checks for RT? You're using this
> compaction sysctl as an RT check somehow? That's gross.
The man-page for mlock says that it guarantees to stay in RAM and/ or
preventing to be moved to swap area. I would however argue that
replacing physical pages in the background should fall under this since
the application can't access them and is blocked while trying. The notes
section (in the man-page) lists "real-time applications" and
"deterministic timing". Therefore I think it makes sense to do this
unconditionally for mlock areas regardless of the sysctl knob.
Security related application probably only care that their memory does
not hit the swap area and probably wouldn't mind 10ms delay.
> This doesn't feel like the right solution.
Sebastian
^ permalink raw reply
* [PATCH] rtla/tests: Test all tracer options in runtime tests
From: Tomas Glozar @ 2026-07-09 9:17 UTC (permalink / raw)
To: Steven Rostedt, Tomas Glozar
Cc: John Kacur, Luis Goncalves, Crystal Wood, Costa Shulyupin,
Wander Lairson Costa, LKML, linux-trace-kernel
Currently, runtime tests only test the osnoise period option
(-p/--period of rtla-osnoise tools, backed by
/sys/kernel/tracing/osnoise/period_us), using the
check_with_osnoise_options function together with a hack relying on long
period (pre-set) timing out if RTLA fails to reset it to the default
value.
Extend tracer option testing to all options used by RTLA; test both RTLA
setting the default option by pre-setting the tracer to a different
value and user-requested value.
The tests are done using a script that reads the tracer values inside an
--on-threshold action, like existing tests for runtime behavior already
do. check_with_osnoise_option is modified to support grep filters, so
that it can be used together with the script pattern.
Assisted-by: Claude:claude-opus-4-6
Signed-off-by: Tomas Glozar <tglozar@redhat.com>
---
tools/tracing/rtla/tests/engine.sh | 41 +++++++++++--------
tools/tracing/rtla/tests/hwnoise.t | 3 ++
tools/tracing/rtla/tests/osnoise.t | 37 +++++++++++++++--
.../tests/scripts/check-osnoise-option.sh | 16 ++++++++
.../rtla/tests/scripts/check-tracefs-value.sh | 11 +++++
tools/tracing/rtla/tests/timerlat.t | 38 +++++++++++++++++
6 files changed, 125 insertions(+), 21 deletions(-)
create mode 100755 tools/tracing/rtla/tests/scripts/check-osnoise-option.sh
create mode 100755 tools/tracing/rtla/tests/scripts/check-tracefs-value.sh
diff --git a/tools/tracing/rtla/tests/engine.sh b/tools/tracing/rtla/tests/engine.sh
index 5bf8453d354d6..4287cd64ac314 100644
--- a/tools/tracing/rtla/tests/engine.sh
+++ b/tools/tracing/rtla/tests/engine.sh
@@ -98,30 +98,37 @@ check() {
}
check_with_osnoise_options() {
- # Do the same as "check", but with pre-set osnoise options.
- # Note: rtla should reset the osnoise options, this is used to test
- # if it indeed does so.
- # Save original arguments
- arg1=$1
- arg2=$2
- arg3=$3
-
- # Apply osnoise options (if not dry run)
+ # Do the same as "check", but with pre-set tracefs options.
+ # Resets osnoise first, then writes the given tracefs option=value
+ # pairs before running the check with NO_RESET_OSNOISE=1.
+ # Arguments: test_name command exit_code expected_output [path=value ...]
+ # Each path is relative to /sys/kernel/tracing/
+ local arg1=$1
+ local arg2=$2
+ local arg3=$3
+ local arg4=$4
+ local opt option value
+
+ # Apply tracefs options (if not dry run)
if [ -n "$TEST_COUNT" ]
then
[ "$NO_RESET_OSNOISE" == 1 ] || reset_osnoise
- shift
- shift
- while shift
+ shift 4
+ for opt in "$@"
do
- [ "$1" == "" ] && continue
- option=$(echo $1 | cut -d '=' -f 1)
- value=$(echo $1 | cut -d '=' -f 2)
- echo "$value" > "/sys/kernel/tracing/osnoise/$option" || return 1
+ [ -z "$opt" ] && continue
+ option="${opt%%=*}"
+ value="${opt#*=}"
+ # Try to apply the option, ignore errors: when pre-setting fails
+ # (e.g. kernel does not know the option), the test itself will likely
+ # also fail.
+ # Throwing an error here would cause the test to be incorrectly
+ # skipped.
+ echo "$value" > "/sys/kernel/tracing/$option"
done
fi
- NO_RESET_OSNOISE=1 check "$arg1" "$arg2" "$arg3"
+ NO_RESET_OSNOISE=1 check "$arg1" "$arg2" "$arg3" "$arg4"
}
check_top_hist() {
diff --git a/tools/tracing/rtla/tests/hwnoise.t b/tools/tracing/rtla/tests/hwnoise.t
index cfe687ff5ee1f..b53d8d440fc50 100644
--- a/tools/tracing/rtla/tests/hwnoise.t
+++ b/tools/tracing/rtla/tests/hwnoise.t
@@ -18,5 +18,8 @@ check "stop the trace if a single sample is higher than 1 us" \
check "enable a trace event trigger" \
"hwnoise -t -e osnoise:irq_noise --trigger=\"hist:key=desc,duration:sort=desc,duration:vals=hitcount\" -d 10s" \
0 "Saving event osnoise:irq_noise hist to osnoise_irq_noise_hist.txt"
+check "verify OSNOISE_IRQ_DISABLE" \
+ "hwnoise -S 1 --on-threshold shell,command=\"$testdir/scripts/check-osnoise-option.sh OSNOISE_IRQ_DISABLE\"" \
+ 2 "^OSNOISE_IRQ_DISABLE=enabled$"
test_end
diff --git a/tools/tracing/rtla/tests/osnoise.t b/tools/tracing/rtla/tests/osnoise.t
index 346a14a860c82..f773156e758fd 100644
--- a/tools/tracing/rtla/tests/osnoise.t
+++ b/tools/tracing/rtla/tests/osnoise.t
@@ -42,11 +42,40 @@ check "hist with --no-index" \
check "hist with --no-summary" \
"osnoise hist --no-summary -d 1s" 0 "" "^count:"
-# Test setting default period by putting an absurdly high period
-# and stopping on threshold.
-# If default period is not set, this will time out.
+# Tracer option tests - verify that rtla correctly sets tracefs options
+# Default tests: poison tracefs with wrong values, verify rtla resets to defaults
check_with_osnoise_options "apply default period" \
- "osnoise hist -s 1" 2 period_us=600000000
+ "osnoise top -q -S 1 --on-threshold shell,command=\"$testdir/scripts/check-tracefs-value.sh osnoise/period_us\"" \
+ 2 "^osnoise/period_us=1000000$" osnoise/period_us=600000000
+check_with_osnoise_options "apply default runtime" \
+ "osnoise top -q -S 1 --on-threshold shell,command=\"$testdir/scripts/check-tracefs-value.sh osnoise/runtime_us\"" \
+ 2 "^osnoise/runtime_us=1000000$" osnoise/runtime_us=100
+check_with_osnoise_options "apply default tracing_thresh" \
+ "osnoise top -q -S 1 --on-threshold shell,command=\"$testdir/scripts/check-tracefs-value.sh tracing_thresh\"" \
+ 2 "^tracing_thresh=0$" tracing_thresh=999999
+check_with_osnoise_options "apply default stop_tracing_us" \
+ "osnoise top -q -S 1 --on-threshold shell,command=\"$testdir/scripts/check-tracefs-value.sh osnoise/stop_tracing_us\"" \
+ 2 "^osnoise/stop_tracing_us=0$" osnoise/stop_tracing_us=999999
+check_with_osnoise_options "apply default stop_tracing_total_us" \
+ "osnoise top -q -s 1 --on-threshold shell,command=\"$testdir/scripts/check-tracefs-value.sh osnoise/stop_tracing_total_us\"" \
+ 2 "^osnoise/stop_tracing_total_us=0$" osnoise/stop_tracing_total_us=999999
+
+# Non-default tracer option tests: verify CLI options correctly set tracefs values
+check_top_q_hist "verify -p sets period_us" \
+ "osnoise TOOL -p 2000000 -S 1 --on-threshold shell,command=\"$testdir/scripts/check-tracefs-value.sh osnoise/period_us\"" \
+ 2 "^osnoise/period_us=2000000$"
+check_top_q_hist "verify -r sets runtime_us" \
+ "osnoise TOOL -r 500000 -S 1 --on-threshold shell,command=\"$testdir/scripts/check-tracefs-value.sh osnoise/runtime_us\"" \
+ 2 "^osnoise/runtime_us=500000$"
+check_top_q_hist "verify -T sets tracing_thresh" \
+ "osnoise TOOL -T 5 -S 1 --on-threshold shell,command=\"$testdir/scripts/check-tracefs-value.sh tracing_thresh\"" \
+ 2 "^tracing_thresh=5$"
+check_top_q_hist "verify -s sets stop_tracing_us" \
+ "osnoise TOOL -s 30 -S 1 --on-threshold shell,command=\"$testdir/scripts/check-tracefs-value.sh osnoise/stop_tracing_us\"" \
+ 2 "^osnoise/stop_tracing_us=30$"
+check_top_q_hist "verify -S sets stop_tracing_total_us" \
+ "osnoise TOOL -S 100 --on-threshold shell,command=\"$testdir/scripts/check-tracefs-value.sh osnoise/stop_tracing_total_us\"" \
+ 2 "^osnoise/stop_tracing_total_us=100$"
# Actions tests
check_top_q_hist "trace output through -t with custom filename" \
diff --git a/tools/tracing/rtla/tests/scripts/check-osnoise-option.sh b/tools/tracing/rtla/tests/scripts/check-osnoise-option.sh
new file mode 100755
index 0000000000000..37c62268cc151
--- /dev/null
+++ b/tools/tracing/rtla/tests/scripts/check-osnoise-option.sh
@@ -0,0 +1,16 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Check if osnoise options are enabled or disabled.
+# Usage: check-osnoise-option.sh <OPTION1> [<OPTION2> ...]
+# Output: one line per option in the format "OPTION=enabled" or "OPTION=disabled"
+
+options=$(tr ' ' '\n' < /sys/kernel/tracing/osnoise/options)
+for name in "$@"; do
+ if echo "$options" | grep -q "^NO_${name}$"; then
+ echo "$name=disabled"
+ elif echo "$options" | grep -q "^${name}$"; then
+ echo "$name=enabled"
+ else
+ echo "$name=unsupported"
+ fi
+done
diff --git a/tools/tracing/rtla/tests/scripts/check-tracefs-value.sh b/tools/tracing/rtla/tests/scripts/check-tracefs-value.sh
new file mode 100755
index 0000000000000..12d0eacd6a85d
--- /dev/null
+++ b/tools/tracing/rtla/tests/scripts/check-tracefs-value.sh
@@ -0,0 +1,11 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+# Read tracefs values and print them.
+# Usage: check-tracefs-value.sh <relative_path1> [<relative_path2> ...]
+# Each path is relative to /sys/kernel/tracing/
+# Output: one line per file in the format "path=value"
+
+for file in "$@"; do
+ read value < "/sys/kernel/tracing/$file"
+ echo "$file=$value"
+done
diff --git a/tools/tracing/rtla/tests/timerlat.t b/tools/tracing/rtla/tests/timerlat.t
index 8193048e8c8ce..aa5b91d88ca4b 100644
--- a/tools/tracing/rtla/tests/timerlat.t
+++ b/tools/tracing/rtla/tests/timerlat.t
@@ -55,6 +55,44 @@ check_top_q_hist "verify -k/--kernel-threads" \
check_top_q_hist "verify -u/--user-threads" \
"timerlat TOOL -u -c 0 -d 10s -T 1 --on-threshold shell,command=$testdir/scripts/check-user-kernel-threads.sh" 2 "0 kernel threads, 1 user threads"
+# Tracer option tests - verify that rtla correctly sets tracefs options
+# Default tests: poison tracefs with wrong values, verify rtla resets to defaults
+check_with_osnoise_options "apply default timerlat_period_us" \
+ "timerlat top -q -T 1 --on-threshold shell,command=\"$testdir/scripts/check-tracefs-value.sh osnoise/timerlat_period_us\"" \
+ 2 "^osnoise/timerlat_period_us=1000$" osnoise/timerlat_period_us=999999
+check_with_osnoise_options "apply default print_stack" \
+ "timerlat top -q -T 1 --on-threshold shell,command=\"$testdir/scripts/check-tracefs-value.sh osnoise/print_stack\"" \
+ 2 "^osnoise/print_stack=0$" osnoise/print_stack=999999
+check_with_osnoise_options "apply default stop_tracing_us" \
+ "timerlat top -q -T 1 --on-threshold shell,command=\"$testdir/scripts/check-tracefs-value.sh osnoise/stop_tracing_us\"" \
+ 2 "^osnoise/stop_tracing_us=0$" osnoise/stop_tracing_us=999999
+check_with_osnoise_options "apply default stop_tracing_total_us" \
+ "timerlat top -q -i 1 --on-threshold shell,command=\"$testdir/scripts/check-tracefs-value.sh osnoise/stop_tracing_total_us\"" \
+ 2 "^osnoise/stop_tracing_total_us=0$" osnoise/stop_tracing_total_us=999999
+
+# Non-default tracer option tests: verify CLI options correctly set tracefs values
+check_top_q_hist "verify -p sets timerlat_period_us" \
+ "timerlat TOOL -p 2000 -T 1 --on-threshold shell,command=\"$testdir/scripts/check-tracefs-value.sh osnoise/timerlat_period_us\"" \
+ 2 "^osnoise/timerlat_period_us=2000$"
+check_top_q_hist "verify -s sets print_stack" \
+ "timerlat TOOL -s 5 -T 1 --on-threshold shell,command=\"$testdir/scripts/check-tracefs-value.sh osnoise/print_stack\"" \
+ 2 "^osnoise/print_stack=5$"
+check_top_q_hist "verify -i sets stop_tracing_us" \
+ "timerlat TOOL -i 2 --on-threshold shell,command=\"$testdir/scripts/check-tracefs-value.sh osnoise/stop_tracing_us\"" \
+ 2 "^osnoise/stop_tracing_us=2$"
+check_top_q_hist "verify -T sets stop_tracing_total_us" \
+ "timerlat TOOL -T 2 --on-threshold shell,command=\"$testdir/scripts/check-tracefs-value.sh osnoise/stop_tracing_total_us\"" \
+ 2 "^osnoise/stop_tracing_total_us=2$"
+check_with_osnoise_options "apply default TIMERLAT_ALIGN" \
+ "timerlat top -q -T 1 --on-threshold shell,command=\"$testdir/scripts/check-osnoise-option.sh TIMERLAT_ALIGN\"" \
+ 2 "^TIMERLAT_ALIGN=disabled$" osnoise/options=TIMERLAT_ALIGN
+check_top_q_hist "verify -A sets TIMERLAT_ALIGN" \
+ "timerlat TOOL -A 100 -T 1 --on-threshold shell,command=\"$testdir/scripts/check-osnoise-option.sh TIMERLAT_ALIGN\"" \
+ 2 "^TIMERLAT_ALIGN=enabled$"
+check_top_q_hist "verify -A sets timerlat_align_us" \
+ "timerlat TOOL -A 100 -T 1 --on-threshold shell,command=\"$testdir/scripts/check-tracefs-value.sh osnoise/timerlat_align_us\"" \
+ 2 "^osnoise/timerlat_align_us=100$"
+
# Histogram tests
check "hist with -b/--bucket-size" \
"timerlat hist -b 1 -d 1s"
--
2.55.0
^ permalink raw reply related
* Re: [PATCH v2 4/4] mm/mlock: migrate folios out of CMA when mlocking a range
From: David Hildenbrand (Arm) @ 2026-07-09 10:04 UTC (permalink / raw)
To: Wandun Chen, vbabka, rostedt, mhiramat, Alexander.Krabler, hughd,
fvdl, bigeasy, linux-mm, linux-kernel, linux-trace-kernel,
linux-rt-devel
Cc: akpm, surenb, mhocko, jackmanb, hannes, ziy, ljs, riel, liam,
harry, jannh, lance.yang, mathieu.desnoyers, matthew.brost,
joshua.hahnjy, rakie.kim, byungchul, gourry, ying.huang, apopple,
pfalcato
In-Reply-To: <20260707125925.3725177-5-chenwandun1@gmail.com>
On 7/7/26 14:59, Wandun Chen wrote:
> From: Wandun Chen <chenwandun@lixiang.com>
>
> The region covered by mlock[all] may contain CMA pages. cma_alloc installs
What about ZONE_MOVABLE where memory is supposed to be migratable?
Also, what about drivers that mmap() CMA memory to user space, and
__mm_populate()->populate_vma_page_range() would actually try mlocking them, and
they actually must remain on CMA areas?
--
Cheers,
David
^ permalink raw reply
page: next (older) | prev (newer) | latest
- recent:[subjects (threaded)|topics (new)|topics (active)]
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox