damon_call() failure was causing the context to be stopped, but
asynchronously by the kdamond thread. To handle the race, the caller had
to stop the context. damon_call() is updated to do the stop on its own.
Remove the damon_stop() call from the damon_call() error handling.
Link: https://lore.kernel.org/20260706140628.87414-12-sj@kernel.org
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
damon_call() failure was causing the context to be stopped, but
asynchronously by the kdamond thread. To handle the race, the caller had
to stop the context. damon_call() is updated to do the stop on its own.
Remove the damon_stop() call from the damon_call() error handling.
Link: https://lore.kernel.org/20260706140628.87414-11-sj@kernel.org
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
damon_stop() was theoretically able to return failure while keeping the
second context for mtier running. mtier stops its contexts one by one
with two damon_stop() call for the reason. damon_stop() is refactored to
always successfully stop all requested DAMON contexts. The two calls are
unnecessary. Use only single damon_stop() call for all contexts.
Link: https://lore.kernel.org/20260706140628.87414-9-sj@kernel.org
Signed-off-by: SJ Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
damon_sample_prcl_start() calls damon_call() right after damon_start() is
succeeded. The kdamond that has started by the damon_start() could be
terminated by itself before or in the middle of the damon_call()
execution. There could be multiple reasons for such a stop including
monitoring target process termination and kdamond_fn() internal memory
allocation failures. In the case, damon_call() will fail and return an
error without cleaning up the DAMON context object. The
damon_sample_prcl_start() caller assumes it would clean up the object,
though. When the user requests to start DAMON again,
damon_sample_prcl_start() is called again, allocates a new DAMON context
object and overwrites the pointer for the previous object. As a result,
the previous context object is leaked.
Safely stop the kdamond and deallocate the context object when the failure
is returned. Note that the kdamond should be stopped first, because
damon_call() failure means not complete termination of the kdamond but
only the fact that the termination process has started.
The user impact shouldn't be that significant because the race is not easy
to happen, and only up to one DAMON context object can be leaked per race.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260628215447.96166-7-sj@kernel.org
Link: https://lore.kernel.org/20260610035214.4850-1-sj@kernel.org [1]
Fixes: a6c33f1054 ("samples/damon/prcl: use damon_call() repeat mode instead of damon_callback")
Signed-off-by: SJ Park <sj@kernel.org>
Reviewed-by: Zenghui Yu <zenghui.yu@linux.dev>
Cc: <stable@vger.kernel.org> # 6.17.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
damon_sample_wsse_start() calls damon_call() right after damon_start() is
succeeded. The kdamond that has started by the damon_start() could be
terminated by itself before or in the middle of the damon_call()
execution. There could be multiple reasons for such a stop including
monitoring target process termination and kdamond_fn() internal memory
allocation failures. In the case, damon_call() will fail and return an
error without cleaning up the DAMON context object. The
damon_sample_wsse_start() caller assumes it would clean up the object,
though. When the user requests to start DAMON again,
damon_sample_wsse_start() is called again, allocates a new DAMON context
object and overwrites the pointer for the previous object. As a result,
the previous context object is leaked.
Safely stop the kdamond and deallocate the context object when the failure
is returned. Note that the kdamond should be stopped first, because
damon_call() failure means not complete termination of the kdamond but
only the fact that the termination process has started.
The user impact shouldn't be that significant because the race is not easy
to happen, and only up to one DAMON context object can be leaked per race.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260628215447.96166-6-sj@kernel.org
Link: https://lore.kernel.org/20260610034828.4632-1-sj@kernel.org [1]
Fixes: cc9c1b8c20 ("samples/damon/wsse: use damon_call() repeat mode instead of damon_callback")
Signed-off-by: SJ Park <sj@kernel.org>
Reviewed-by: Zenghui Yu <zenghui.yu@linux.dev>
Cc: <stable@vger.kernel.org> # 6.17.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
damon_sample_mtier_stop() assumes its damon_stop() call will always
successfully stops the two DAMON contexts. Hence it deallocates the two
DAMON contexts after the damon_stop() call. However, if a given context
is already stopped, damon_stop() fails and returns an error while letting
the DAMON contexts that have not yet stopped keep running. This kind of
unexpected early DAMON context stops could happen due to memory allocation
failures in kdamond_fn(). Because damon_sample_mtier_stop() just
deallocates all DAMON contexts with damon_target and damon_region objects
that are linked to the contexts, the execution of the unstopped DAMON
context (kdamond) ends up using the memory that freed (use-after-free).
Fix the issue by separating the damon_stop() to be invoked per context.
Note that DAMON_SYSFS also allows multiple DAMON contexts execution. But,
it calls damon_stop() for each context one by one. Hence this issue is
only in mtier.
For the long term, it would be better to refactor damon_stop() to always
ensure stopping all contexts regardless of the failures in the middle.
Make this fix in the current way, though, to keep it simple and easy to
backport. I will do the refactoring later.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260628215447.96166-5-sj@kernel.org
Link: https://lore.kernel.org/20260609014219.3013-1-sj@kernel.org [1]
Fixes: 82a08bde3c ("samples/damon: implement a DAMON module for memory tiering")
Signed-off-by: SJ Park <sj@kernel.org>
Reviewed-by: Zenghui Yu <zenghui.yu@linux.dev>
Cc: <stable@vger.kernel.org> # 6.16.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
damon_sample_mtier_start() callers assume it will clean up resources when
it fails. And the function does the cleanup for context buildup failures.
However, it is not doing the cleanup for damon_start() failure.
As a result, when damon_start() fails, it could leak the memory for DAMON
context. Also, if damon_start() fails for only the second context, the
first context will indefinitely run, and avoid starting other DAMON
contexts since it is running in the exclusive mode. Stop possibly started
DAMON context and free the contexts in case of the failure to fix the
issues.
Note that the issue can reliably be reproduced because the module calls
damon_start() in the exclusive mode. For example,
$ sudo damo start
$ echo Y | sudo tee /sys/module/damon_sample_mtier/parameters/enabled
$ sudo cat /proc/allocinfo | grep damon_new_ctx
Because the first command is running another DAMON instance, the second
command fails the damon_start() call because the new DAMON instance cannot
exclusively run. And without this fix, by repeating the second and the
third commands above, we can show the memory consumption is only
increasing due to the leaks. It requires the sudo permission though.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260628215447.96166-4-sj@kernel.org
Link: https://lore.kernel.org/20260608112455.274231F00893@smtp.kernel.org [1]
Fixes: 82a08bde3c ("samples/damon: implement a DAMON module for memory tiering")
Signed-off-by: SJ Park <sj@kernel.org>
Reviewed-by: Zenghui Yu <zenghui.yu@linux.dev>
Cc: <stable@vger.kernel.org> # 6.16.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
damon_sample_prcl_start() callers assume it will clean up resources when
it fails. And the function does the cleanup for context buildup failures.
However, it is not doing the cleanup for damon_start() failure. As a
result, when damon_start() fails, it leaks the memory for DAMON context.
Free the context in case of the failure to fix the issues.
Note that the issue can reliably be reproduced because the module calls
damon_start() in the exclusive mode. For example,
$ sudo damo start
$ echo $$ | sudo tee /sys/module/damon_sample_prcl/parameters/target_pid
$ echo Y | sudo tee /sys/module/damon_sample_prcl/parameters/enabled
$ sudo cat /proc/allocinfo | grep damon_new_ctx
Because the first command is running another DAMON instance, the third
command fails the damon_start() call because the new DAMON instance cannot
exclusively run. And without this fix, by repeating the third and the
fourth commands above, we can show the memory consumption is only
increasing due to the leaks. It requires the sudo permission though.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260628215447.96166-3-sj@kernel.org
Link: https://lore.kernel.org/20260609145814.70163-1-sj@kernel.org [1]
Fixes: 2aca254620 ("samples/damon: introduce a skeleton of a smaple DAMON module for proactive reclamation")
Signed-off-by: SJ Park <sj@kernel.org>
Reviewed-by: Zenghui Yu <zenghui.yu@linux.dev>
Cc: <stable@vger.kernel.org> # 6.14.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "samples/damon: handle damon_{start,stop}() failures".
All DAMON sample modules are not correctly handling failures from
damon_start(). Among those, mtier also has an additional problem for
handling of damon_stop() failures. wsse and prcl also have a problem in
their damon_call() failure handling. As a result, memory leaks, next
DAMON operation disruptions, and use-after-free can happen. Fix those.
Note that only the damon_start() failure caused issues can reliably be
reproduced. Reproducing those issues require the admin permission,
though.
This patch (of 6):
damon_sample_wsse_start() callers assume it will clean up resources when
it fails. And the function does the cleanup for context buildup failures.
However, it is not doing the cleanup for damon_start() failure. As a
result, when damon_start() fails, it leaks the memory for DAMON context.
Free the context in case of the failure to fix the issues.
Note that the issue can reliably be reproduced because the module calls
damon_start() in the exclusive mode. For example,
$ sudo damo start
$ echo $$ | sudo tee /sys/module/damon_sample_wsse/parameters/target_pid
$ echo Y | sudo tee /sys/module/damon_sample_wsse/parameters/enabled
$ sudo cat /proc/allocinfo | grep damon_new_ctx
Because the first command is running another DAMON instance, the third
command fails the damon_start() call because the new DAMON instance cannot
exclusively run. And without this fix, by repeating the third and the
fourth commands above, we can show the memory consumption is only
increasing due to the leaks. It requires the sudo permission though.
The issue was discovered [1] by Sashiko.
Link: https://lore.kernel.org/20260628215447.96166-2-sj@kernel.org
Link: https://lore.kernel.org/20260609145814.70163-1-sj@kernel.org [1]
Fixes: b757c6cfc6 ("samples/damon/wsse: start and stop DAMON as the user requests")
Signed-off-by: SJ Park <sj@kernel.org>
Reviewed-by: Zenghui Yu <zenghui.yu@linux.dev>
Cc: <stable@vger.kernel.org> # 6.14.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The ftrace-ops sample exposes nr_function_calls as a module parameter
and uses it as the divisor when printing the measured time per call.
Loading the module with nr_function_calls=0 skips the benchmark loop and
then divides the elapsed time by zero, crashing the kernel during sample
module initialization.
Keep accepting the parameter value, but report -1LL as the per-call
duration when the call count is zero instead of dividing by it.
Link: https://patch.msgid.link/20260629152616.107080.e19bfbed249c.ftrace-ops-zero-function-calls-div0@trailofbits.com
Assisted-by: Codex:gpt-5.5-cyber-preview
Signed-off-by: Samuel Moelius <sam.moelius@trailofbits.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Backmerge to pull in commit 21fcb222f0 ("drm: Remove DRIVER_GEM_GPUVA
feature flag"), which a Tyr patch series depends on.
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
The current implementation creates a 4K array and move it into the box.
Klint reports that this causes excesssive stack usage:
warning: stack size of `create_file_write` is 4472 bytes, exceeds the 2048-byte limit
--> samples/rust/rust_debugfs_scoped.rs:54:1
|
54 | / fn create_file_write(
55 | | mod_data: &ModuleData,
56 | | reader: &mut kernel::uaccess::UserSliceReader,
57 | | ) -> Result {
| |___________^
|
= note: the stack size is inferred from instruction `sub $0x1178,%rsp` at .text+2205
Use pin-init to create the array in-place instead.
Fixes: f656279afd ("samples: rust: debugfs_scoped: add example for blobs")
Signed-off-by: Gary Guo <gary@garyguo.net>
Reviewed-by: Alexandre Courbot <acourbot@nvidia.com>
Link: https://patch.msgid.link/20260716144144.3665719-1-gary@kernel.org
[ Make the patch rustfmtcheck complient. - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Currently the lifetime on `Core` and `CoreInternal` is covariant. This
means that they can be coerced into shorter living lifetimes. On `probe`
function, signature has `&'bound Device<Core<'a>>`; the type's wellformness
would imply `'a: 'bound` and thus the type can be coerced `&'bound
Device<Core<'bound>>`, defeating the purpose of having the lifetime bound
to prevent users of the `Core` type to escape the function.
Fix this by making the lifetime invariant, so the coercion is impossible.
The lifetime here only needs to be "branded" so it does not coerce or unify
with other lifetimes, so we do not need to ensure `'bound: 'a`.
This requires modifying `nova-core` which relies on this implied bound due
to pre-2024 capture rule. The "use" bound can be removed if built with
edition 2024.
Fixes: 24799831d6 ("rust: device: make Core and CoreInternal lifetime-parameterized")
Signed-off-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260713201455.640151-1-gary@kernel.org
[ Fixup the debugfs sample to use an explicit lifetime instead of
Core<'_>. - Danilo ]
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
With the introduction of container_of-style BTF typecasting and
per-CPU variable access support in trace probes, we need a way to
verify their functionality and prevent regressions.
Add a new ftrace kselftest and update the trace event sample module
to test and validate these features.
Specifically, update the trace-events-sample module to set up a
periodic timer whose callback accesses a per-CPU counter. Introduce
a new sample trace event, foo_timer_fn, to trace this callback
and log the current counter value.
Then, add a new test case, btf_probe_event.tc, which defines a
dynamic probe on the timer callback. The probe uses BTF typecasting
to recover the parent structure from the timer argument and
this_cpu_read() to fetch the per-CPU counter. The test verifies
the integrity of the implementation by ensuring the values
recorded by the dynamic probe match those from the static tracepoint.
Link: https://lore.kernel.org/all/178271368625.1176915.13502654445483530822.stgit@devnote2/
Assisted-by: Antigravity:gemini-3.5-flash
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
I/O type generalization and projection
This series presents a major rework of I/O types, as a summary:
- Make I/O regions typed. The existing untyped region still exists
with a dynamically sized `Region` type.
- Create I/O view types to represent subregion of a full I/O region mapped.
A projection macro is added to allow safely create such subviews.
- Split I/O traits, make I/O views play a central role, avoid
duplicate monomorphization and less `unsafe` code.
- Add a `SysMem` backend, and make `Coherent` implement `Io`.
- Add copying methods (memcpy_{from,to}io and friends).
This series generalize `Mmio` type from just an untyped region to typed
representations (so `MmioRaw<T>` is `__iomem *T`). This allows us to remove
the `IoKnownSize` trait; the information is sourced from just the pointer
from the `KnownSize` trait instead.
Building on top of that, `Mmio` and `ConfigSpace` have been converted to
typed views of I/O regions rather than just a big chunk of untyped I/O
memory. These changes made it possible to implement `Io` trait for
`Coherent<T>`.
Shared system memory, `SysMem` is also added to the series, given it
similarity in implementation compared to `Coherent`. In fact, the series
use `SysMem` to implement `Coherent`'s I/O methods.
Built on these generalization, this series add `io_project!()`.
`io_project!()` performs a safe way to project a bigger view to a small
subviews, and some Nova code has been converted in this series to
demonstrate cleanups possible with this addition.
New `io_read!()`, `io_write!()` has been added that supersedes
`dma_read!()`, `dma_write!()` macro. Although, they work for primitives
only (to be exact, types that the backend is `IoCapable` of).
One feature that was lost from the old `dma_read!()` and `dma_write!()`
series was the ability to read/write a large structs. However, the
semantics was unclear to begin with, as there was no guarantee about their
atomicity even for structs that were small enough to fit in u32.
Suggested-by: Danilo Krummrich <dakr@kernel.org>
Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/Generic.20I.2FO.20backends/near/571198078
This is a stable tag for other trees to merge.
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Gary Guo <gary@garyguo.net> says:
This series presents a major rework of I/O types, as a summary:
- Make I/O regions typed. The existing untyped region still exists
with a dynamically sized `Region` type.
- Create I/O view types to represent subregion of a full I/O region mapped.
A projection macro is added to allow safely create such subviews.
- Split I/O traits, make I/O views play a central role, avoid
duplicate monomorphization and less `unsafe` code.
- Add a `SysMem` backend, and make `Coherent` implement `Io`.
- Add copying methods (memcpy_{from,to}io and friends).
This series generalize `Mmio` type from just an untyped region to typed
representations (so `MmioRaw<T>` is `__iomem *T`). This allows us to remove
the `IoKnownSize` trait; the information is sourced from just the pointer
from the `KnownSize` trait instead.
Building on top of that, `Mmio` and `ConfigSpace` have been converted to
typed views of I/O regions rather than just a big chunk of untyped I/O
memory. These changes made it possible to implement `Io` trait for
`Coherent<T>`.
Shared system memory, `SysMem` is also added to the series, given it
similarity in implementation compared to `Coherent`. In fact, the series
use `SysMem` to implement `Coherent`'s I/O methods.
Built on these generalization, this series add `io_project!()`.
`io_project!()` performs a safe way to project a bigger view to a small
subviews, and some Nova code has been converted in this series to
demonstrate cleanups possible with this addition.
New `io_read!()`, `io_write!()` has been added that supersedes
`dma_read!()`, `dma_write!()` macro. Although, they work for primitives
only (to be exact, types that the backend is `IoCapable` of).
One feature that was lost from the old `dma_read!()` and `dma_write!()`
series was the ability to read/write a large structs. However, the
semantics was unclear to begin with, as there was no guarantee about their
atomicity even for structs that were small enough to fit in u32.
Suggested-by: Danilo Krummrich <dakr@kernel.org>
Link: https://rust-for-linux.zulipchat.com/#narrow/channel/288089-General/topic/Generic.20I.2FO.20backends/near/571198078
Link: https://patch.msgid.link/20260706-io_projection-v6-0-72cd5d055d54@garyguo.net
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Mark Brown
SJ ParkandAndrew Morton
Asier GutierrezandAndrew Morton
Steven Rostedt
Samuel MoeliusandSteven Rostedt
Danilo Krummrich
Guru Das SrinageshandDanilo Krummrich
Markus ProbstandDanilo Krummrich
Gary GuoandDanilo Krummrich
Masami Hiramatsu (Google)