linux-kernel - [PATCH 1/1] mm: Fix memory leak on mm

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Date:   Thu, 30 Mar 2023 09:38:22 -0400
From:   Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-kernel@...r.kernel.org,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        Shakeel Butt <shakeelb@...gle.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        linux-mm@...ck.org, stable@...r.kernel.org
Subject: [PATCH 1/1] mm: Fix memory leak on mm_init error handling

commit f1a7941243c1 ("mm: convert mm's rss stats into percpu_counter")
introduces a memory leak by missing a call to destroy_context() when a
percpu_counter fails to allocate.

Before introducing the per-cpu counter allocations, init_new_context()
was the last call that could fail in mm_init(), and thus there was no
need to ever invoke destroy_context() in the error paths. Adding the
following percpu counter allocations adds error paths after
init_new_context(), which means its associated destroy_context() needs
to be called when percpu counters fail to allocate.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Shakeel Butt <shakeelb@...gle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Marek Szyprowski <m.szyprowski@...sung.com>
Cc: linux-mm@...ck.org
Cc: stable@...r.kernel.org # 6.2
---
 kernel/fork.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/kernel/fork.c b/kernel/fork.c
index c0257cbee093..c983c4fe3090 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1171,6 +1171,7 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
 fail_pcpu:
 	while (i > 0)
 		percpu_counter_destroy(&mm->rss_stat[--i]);
+	destroy_context(mm);
 fail_nocontext:
 	mm_free_pgd(mm);
 fail_nopgd:
-- 
2.25.1