linux-kernel - Re: [PATCH 1/2] mm: vmpressure: don't need call kfree if kstrndup fails

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Message-Id: <20200212204827.df1de9015a3c03c79a8d7155@linux-foundation.org>
Date:   Wed, 12 Feb 2020 20:48:27 -0800
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Yang Shi <yang.shi@...ux.alibaba.com>
Cc:     David Hildenbrand <david@...hat.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] mm: vmpressure: don't need call kfree if kstrndup
 fails

On Wed, 12 Feb 2020 19:14:27 -0800 Yang Shi <yang.shi@...ux.alibaba.com> wrote:

> On 2/12/20 3:21 AM, David Hildenbrand wrote:
> > On 11.02.20 06:24, Yang Shi wrote:
> >> When kstrndup fails (returns NULL) there is no memory is allocated by
> >> kmalloc, so no need to call kfree().
> > "When kstrndup fails, no memory was allocated and we can exit directly."
> 
> Thanks for correcting the commit log.
> 
> Andrew, do you prefer I send an updated version or you would just update 
> the patch in -mm tree?

I have already done this.

From: Yang Shi <yang.shi@...ux.alibaba.com>
Subject: mm: vmpressure: don't need call kfree if kstrndup fails

When kstrndup fails, no memory was allocated and we can exit directly.

[david@...hat.com: reword changelog]
Link: http://lkml.kernel.org/r/1581398649-125989-1-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@...ux.alibaba.com>
Reviewed-by: Andrew Morton <akpm@...ux-foundation.org>
Reviewed-by: David Hildenbrand <david@...hat.com>
Acked-by: David Rientjes <rientjes@...gle.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---

 mm/vmpressure.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

--- a/mm/vmpressure.c~mm-vmpressure-dont-need-call-kfree-if-kstrndup-fails
+++ a/mm/vmpressure.c
@@ -371,10 +371,8 @@ int vmpressure_register_event(struct mem
 	int ret = 0;
 
 	spec_orig = spec = kstrndup(args, MAX_VMPRESSURE_ARGS_LEN, GFP_KERNEL);
-	if (!spec) {
-		ret = -ENOMEM;
-		goto out;
-	}
+	if (!spec)
+		return -ENOMEM;
 
 	/* Find required level */
 	token = strsep(&spec, ",");
_