FAILED: patch "[PATCH] mm/damon/core: make damon_start() waits until kdamond_fn()" failed to apply to 6.1-stable tree
Subsystems (3)
[email protected]
maintainerThe patch below does not apply to the 6.1-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 <[email protected]>.
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-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 6376a824595607e99d032a39ba3394988b4fce96
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2023121849-ambulance-violate-e5b2@gregkh' --subject-prefix 'PATCH 6.1.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") 2f5bef5a590b ("mm/damon/core: update monitoring results for new monitoring attributes")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From 6376a824595607e99d032a39ba3394988b4fce96 Mon Sep 17 00:00:00 2001
From: SeongJae Park <[email protected]>
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().
include/linux/damon.h +2 -0
@@ -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;
mm/damon/core.c +6 -0
@@ -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)
SeongJae Park
maintainerPATCH 1/1 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().
--- include/linux/damon.h | 3 +++ mm/damon/core.c | 7 +++++++ 2 files changed, 10 insertions(+)
include/linux/damon.h +3 -0
@@ -8,6 +8,7 @@#ifndef _DAMON_H_#define _DAMON_H_ +#include <linux/completion.h> #include <linux/mutex.h> #include <linux/time64.h> #include <linux/types.h>
@@ -452,6 +453,8 @@ 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;
mm/damon/core.c +7 -0
@@ -383,6 +383,8 @@ 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 ;
@@ -519,11 +521,14 @@ 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);
@@ -1147,6 +1152,8 @@ 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))
Signature · 1 line
2.34.1