github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-05-30 01:53:29 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

mm/damon/core: introduce damon_call_control->dealloc_on_cancel

Browse Source 
Patch series "mm/damon/sysfs: fix refresh_ms control overwriting on
multi-kdamonds usages".

Automatic esssential DAMON/DAMOS status update feature of DAMON sysfs
interface (refresh_ms) is broken [1] for multiple DAMON contexts
(kdamonds) use case, since it uses a global single damon_call_control
object for all created DAMON contexts.  The fields of the object,
particularly the list field is over-written for the contexts and it makes
unexpected results including user-space hangup and kernel crashes [2]. 
Fix it by extending damon_call_control for the use case and updating the
usage on DAMON sysfs interface to use per-context dynamically allocated
damon_call_control object.


This patch (of 2):

When damon_call_control->repeat is set, damon_call() is executed
asynchronously, and is eventually canceled when kdamond finishes.  If the
damon_call_control object is dynamically allocated, finding the place to
deallocate the object is difficult.  Introduce a new damon_call_control
field, namely dealloc_on_cancel, to ask the kdamond deallocates those
dynamically allocated objects when those are canceled.

Link: https://lkml.kernel.org/r/20250908201513.60802-3-sj@kernel.org
Link: https://lkml.kernel.org/r/20250908201513.60802-2-sj@kernel.org
Fixes: d809a7c64b ("mm/damon/sysfs: implement refresh_ms file internal work")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Yunjeong Mun <yunjeong.mun@sk.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
SeongJae Park 2025-09-08 13:15:12 -07:00 committed by Andrew Morton
parent 2da6de30e6
commit e6a0deb6fa
2 changed files with 8 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/linux/damon.h
View File

@ -636,6 +636,7 @@ struct damon_operations {
* @data: Data that will be passed to @fn.
* @repeat: Repeat invocations.
* @return_code: Return code from @fn invocation.
* @dealloc_on_cancel: De-allocate when canceled.
*
* Control damon_call(), which requests specific kdamond to invoke a given
* function. Refer to damon_call() for more details.
@ -645,6 +646,7 @@ struct damon_call_control {
void *data;
bool repeat;
int return_code;
bool dealloc_on_cancel;
/* private: internal use only */
/* informs if the kdamond finished handling of the request */
struct completion completion;

8
mm/damon/core.c
View File

@ -2479,10 +2479,14 @@ static void kdamond_call(struct damon_ctx *ctx, bool cancel)
mutex_lock(&ctx->call_controls_lock);
list_del(&control->list);
mutex_unlock(&ctx->call_controls_lock);
if (!control->repeat)
if (!control->repeat) {
complete(&control->completion);
else
} else if (control->canceled && control->dealloc_on_cancel) {
kfree(control);
continue;
} else {
list_add(&control->list, &repeat_controls);
}
}
control = list_first_entry_or_null(&repeat_controls,
struct damon_call_control, list);