+ mm-damon-dbgfs-use-__gfp_nowarn-for-user-specified-size-buffer-allocation.patch added to -mm tree

+ mm-damon-dbgfs-use-__gfp_nowarn-for-user-specified-size-buffer-allocation.patch added to -mm tree

[akpm]

The patch titled
     Subject: mm/damon/dbgfs: use '__GFP_NOWARN' for user-specified size buffer allocation
has been added to the -mm tree.  Its filename is
     mm-damon-dbgfs-use-__gfp_nowarn-for-user-specified-size-buffer-allocation.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-damon-dbgfs-use-__gfp_nowarn-for-user-specified-size-buffer-allocation.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-damon-dbgfs-use-__gfp_nowarn-for-user-specified-size-buffer-allocation.patch

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------------------------------------------------------
From: SeongJae Park <sj@kernel.org>
Subject: mm/damon/dbgfs: use '__GFP_NOWARN' for user-specified size buffer allocation

Patch series "DAMON fixes".


This patch (of 2):

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.

Link: https://lkml.kernel.org/r/20211110145758.16558-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20211110145758.16558-2-sj@kernel.org
Fixes: 4bc05954d007 ("mm/damon: implement a debugfs-based user space interface")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/damon/dbgfs.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

--- a/mm/damon/dbgfs.c~mm-damon-dbgfs-use-__gfp_nowarn-for-user-specified-size-buffer-allocation
+++ a/mm/damon/dbgfs.c
@@ -32,7 +32,7 @@ static char *user_input_str(const char _
 	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
 	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(s
 	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(st
 	char *kbuf;
 	ssize_t len;
 
-	kbuf = kmalloc(count, GFP_KERNEL);
+	kbuf = kmalloc(count, GFP_KERNEL | __GFP_NOWARN);
 	if (!kbuf)
 		return -ENOMEM;
 
_

Patches currently in -mm which might be from sj@kernel.org are

mm-damon-dbgfs-use-__gfp_nowarn-for-user-specified-size-buffer-allocation.patch
mm-damon-dbgfs-fix-missed-use-of-damon_dbgfs_lock.patch