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From: SeongJae Park <sj@kernel.org>
To: akpm@linux-foundation.org
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	SeongJae Park <sj@kernel.org>
Subject: [PATCH 1/2] mm/damon/dbgfs: Use '__GFP_NOWARN' for user-specified size buffer allocation
Date: Wed, 10 Nov 2021 14:57:57 +0000	[thread overview]
Message-ID: <20211110145758.16558-2-sj@kernel.org> (raw)
In-Reply-To: <20211110145758.16558-1-sj@kernel.org>

DAMON users can trigger below warning in '__alloc_pages()' by invoking
write() to some DAMON debugfs files with arbitrarily high count
argument, because DAMON debugfs interface allocates some buffers based
on the user-specified 'count'.

        if (unlikely(order >= MAX_ORDER)) {
                WARN_ON_ONCE(!(gfp & __GFP_NOWARN));
                return NULL;
        }

Because the DAMON debugfs interface code checks failure of the
'kmalloc()', this commit simply suppresses the warnings by adding
'__GFP_NOWARN' flag.

Fixes: 4bc05954d007 ("mm/damon: implement a debugfs-based user space interface")
Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/dbgfs.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
index eccc14b34901..8ce1311ac533 100644
--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -32,7 +32,7 @@ static char *user_input_str(const char __user *buf, size_t count, loff_t *ppos)
 	if (*ppos)
 		return ERR_PTR(-EINVAL);
 
-	kbuf = kmalloc(count + 1, GFP_KERNEL);
+	kbuf = kmalloc(count + 1, GFP_KERNEL | __GFP_NOWARN);
 	if (!kbuf)
 		return ERR_PTR(-ENOMEM);
 
@@ -133,7 +133,7 @@ static ssize_t dbgfs_schemes_read(struct file *file, char __user *buf,
 	char *kbuf;
 	ssize_t len;
 
-	kbuf = kmalloc(count, GFP_KERNEL);
+	kbuf = kmalloc(count, GFP_KERNEL | __GFP_NOWARN);
 	if (!kbuf)
 		return -ENOMEM;
 
@@ -452,7 +452,7 @@ static ssize_t dbgfs_init_regions_read(struct file *file, char __user *buf,
 	char *kbuf;
 	ssize_t len;
 
-	kbuf = kmalloc(count, GFP_KERNEL);
+	kbuf = kmalloc(count, GFP_KERNEL | __GFP_NOWARN);
 	if (!kbuf)
 		return -ENOMEM;
 
@@ -578,7 +578,7 @@ static ssize_t dbgfs_kdamond_pid_read(struct file *file,
 	char *kbuf;
 	ssize_t len;
 
-	kbuf = kmalloc(count, GFP_KERNEL);
+	kbuf = kmalloc(count, GFP_KERNEL | __GFP_NOWARN);
 	if (!kbuf)
 		return -ENOMEM;
 
-- 
2.17.1


  reply	other threads:[~2021-11-10 14:58 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-10 14:57 [PATCH 0/2] DAMON fixes SeongJae Park
2021-11-10 14:57 ` SeongJae Park [this message]
2021-11-10 14:57 ` [PATCH 2/2] mm/damon/dbgfs: Fix missed use of damon_dbgfs_lock SeongJae Park
2021-11-16  3:42 ` [PATCH 0/2] DAMON fixes Andrew Morton

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