* FAILED: patch "[PATCH] mm/damon/core: make damon_start() waits until kdamond_fn()" failed to apply to 6.6-stable tree
@ 2023-12-18 7:06 gregkh
2023-12-18 17:59 ` [PATCH 6.6.y] mm/damon/core: make damon_start() waits until kdamond_fn() starts SeongJae Park
0 siblings, 1 reply; 2+ messages in thread
From: gregkh @ 2023-12-18 7:06 UTC (permalink / raw)
To: sj, acsjakub, akpm, changbin.du, stable; +Cc: stable
The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.
To reproduce the conflict and resubmit, you may use the following commands:
git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 6376a824595607e99d032a39ba3394988b4fce96
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2023121843-pension-tactile-868b@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..
Possible dependencies:
6376a8245956 ("mm/damon/core: make damon_start() waits until kdamond_fn() starts")
4472edf63d66 ("mm/damon/core: use number of passed access sampling as a timer")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 6376a824595607e99d032a39ba3394988b4fce96 Mon Sep 17 00:00:00 2001
From: SeongJae Park <sj@kernel.org>
Date: Fri, 8 Dec 2023 17:50:18 +0000
Subject: [PATCH] mm/damon/core: make damon_start() waits until kdamond_fn()
starts
The cleanup tasks of kdamond threads including reset of corresponding
DAMON context's ->kdamond field and decrease of global nr_running_ctxs
counter is supposed to be executed by kdamond_fn(). However, commit
0f91d13366a4 ("mm/damon: simplify stop mechanism") made neither
damon_start() nor damon_stop() ensure the corresponding kdamond has
started the execution of kdamond_fn().
As a result, the cleanup can be skipped if damon_stop() is called fast
enough after the previous damon_start(). Especially the skipped reset
of ->kdamond could cause a use-after-free.
Fix it by waiting for start of kdamond_fn() execution from
damon_start().
Link: https://lkml.kernel.org/r/20231208175018.63880-1-sj@kernel.org
Fixes: 0f91d13366a4 ("mm/damon: simplify stop mechanism")
Signed-off-by: SeongJae Park <sj@kernel.org>
Reported-by: Jakub Acs <acsjakub@amazon.de>
Cc: Changbin Du <changbin.du@intel.com>
Cc: Jakub Acs <acsjakub@amazon.de>
Cc: <stable@vger.kernel.org> # 5.15.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
diff --git a/include/linux/damon.h b/include/linux/damon.h
index ab2f17d9926b..e00ddf1ed39c 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -559,6 +559,8 @@ struct damon_ctx {
* update
*/
unsigned long next_ops_update_sis;
+ /* for waiting until the execution of the kdamond_fn is started */
+ struct completion kdamond_started;
/* public: */
struct task_struct *kdamond;
diff --git a/mm/damon/core.c b/mm/damon/core.c
index ce1562783e7e..3a05e71509b9 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -445,6 +445,8 @@ struct damon_ctx *damon_new_ctx(void)
if (!ctx)
return NULL;
+ init_completion(&ctx->kdamond_started);
+
ctx->attrs.sample_interval = 5 * 1000;
ctx->attrs.aggr_interval = 100 * 1000;
ctx->attrs.ops_update_interval = 60 * 1000 * 1000;
@@ -668,11 +670,14 @@ static int __damon_start(struct damon_ctx *ctx)
mutex_lock(&ctx->kdamond_lock);
if (!ctx->kdamond) {
err = 0;
+ reinit_completion(&ctx->kdamond_started);
ctx->kdamond = kthread_run(kdamond_fn, ctx, "kdamond.%d",
nr_running_ctxs);
if (IS_ERR(ctx->kdamond)) {
err = PTR_ERR(ctx->kdamond);
ctx->kdamond = NULL;
+ } else {
+ wait_for_completion(&ctx->kdamond_started);
}
}
mutex_unlock(&ctx->kdamond_lock);
@@ -1433,6 +1438,7 @@ static int kdamond_fn(void *data)
pr_debug("kdamond (%d) starts\n", current->pid);
+ complete(&ctx->kdamond_started);
kdamond_init_intervals_sis(ctx);
if (ctx->ops.init)
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [PATCH 6.6.y] mm/damon/core: make damon_start() waits until kdamond_fn() starts
2023-12-18 7:06 FAILED: patch "[PATCH] mm/damon/core: make damon_start() waits until kdamond_fn()" failed to apply to 6.6-stable tree gregkh
@ 2023-12-18 17:59 ` SeongJae Park
0 siblings, 0 replies; 2+ messages in thread
From: SeongJae Park @ 2023-12-18 17:59 UTC (permalink / raw)
To: stable; +Cc: SeongJae Park, acsjakub, akpm, changbin.du, damon
The cleanup tasks of kdamond threads including reset of corresponding
DAMON context's ->kdamond field and decrease of global nr_running_ctxs
counter is supposed to be executed by kdamond_fn(). However, commit
0f91d13366a4 ("mm/damon: simplify stop mechanism") made neither
damon_start() nor damon_stop() ensure the corresponding kdamond has
started the execution of kdamond_fn().
As a result, the cleanup can be skipped if damon_stop() is called fast
enough after the previous damon_start(). Especially the skipped reset
of ->kdamond could cause a use-after-free.
Fix it by waiting for start of kdamond_fn() execution from
damon_start().
Link: https://lkml.kernel.org/r/20231208175018.63880-1-sj@kernel.org
Fixes: 0f91d13366a4 ("mm/damon: simplify stop mechanism")
Signed-off-by: SeongJae Park <sj@kernel.org>
Reported-by: Jakub Acs <acsjakub@amazon.de>
Cc: Changbin Du <changbin.du@intel.com>
Cc: Jakub Acs <acsjakub@amazon.de>
Cc: <stable@vger.kernel.org> # 5.15.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
(cherry picked from commit 6376a824595607e99d032a39ba3394988b4fce96)
---
include/linux/damon.h | 2 ++
mm/damon/core.c | 7 +++++++
2 files changed, 9 insertions(+)
diff --git a/include/linux/damon.h b/include/linux/damon.h
index c70cca8a839f..e9e8ed92567a 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -524,6 +524,8 @@ struct damon_ctx {
/* private: internal use only */
struct timespec64 last_aggregation;
struct timespec64 last_ops_update;
+ /* for waiting until the execution of the kdamond_fn is started */
+ struct completion kdamond_started;
/* public: */
struct task_struct *kdamond;
diff --git a/mm/damon/core.c b/mm/damon/core.c
index fd5be73f699f..191bc87b2441 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -423,6 +423,8 @@ struct damon_ctx *damon_new_ctx(void)
if (!ctx)
return NULL;
+ init_completion(&ctx->kdamond_started);
+
ctx->attrs.sample_interval = 5 * 1000;
ctx->attrs.aggr_interval = 100 * 1000;
ctx->attrs.ops_update_interval = 60 * 1000 * 1000;
@@ -626,11 +628,14 @@ static int __damon_start(struct damon_ctx *ctx)
mutex_lock(&ctx->kdamond_lock);
if (!ctx->kdamond) {
err = 0;
+ reinit_completion(&ctx->kdamond_started);
ctx->kdamond = kthread_run(kdamond_fn, ctx, "kdamond.%d",
nr_running_ctxs);
if (IS_ERR(ctx->kdamond)) {
err = PTR_ERR(ctx->kdamond);
ctx->kdamond = NULL;
+ } else {
+ wait_for_completion(&ctx->kdamond_started);
}
}
mutex_unlock(&ctx->kdamond_lock);
@@ -1370,6 +1375,8 @@ static int kdamond_fn(void *data)
pr_debug("kdamond (%d) starts\n", current->pid);
+ complete(&ctx->kdamond_started);
+
if (ctx->ops.init)
ctx->ops.init(ctx);
if (ctx->callback.before_start && ctx->callback.before_start(ctx))
--
2.34.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
end of thread, other threads:[~2023-12-18 18:00 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
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2023-12-18 7:06 FAILED: patch "[PATCH] mm/damon/core: make damon_start() waits until kdamond_fn()" failed to apply to 6.6-stable tree gregkh
2023-12-18 17:59 ` [PATCH 6.6.y] mm/damon/core: make damon_start() waits until kdamond_fn() starts SeongJae Park
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