From: Joe Perches <joe@perches.com>
To: Daniel Xu <dxu@dxuuu.xyz>,
cgroups@vger.kernel.org, tj@kernel.org, lizefan@huawei.com,
hannes@cmpxchg.org
Cc: shakeelb@google.com, linux-kernel@vger.kernel.org,
gregkh@linuxfoundation.org, kernel-team@fb.com
Subject: Re: [PATCH v2 1/4] kernfs: kvmalloc xattr value instead of kmalloc
Date: Fri, 06 Mar 2020 00:49:51 -0800 [thread overview]
Message-ID: <58c6e6dafabea52e5b030d18b83c13e4f43ab8e3.camel@perches.com> (raw)
In-Reply-To: <20200305211632.15369-2-dxu@dxuuu.xyz>
On Thu, 2020-03-05 at 13:16 -0800, Daniel Xu wrote:
> It's not really necessary to have contiguous physical memory for xattr
> values. We no longer need to worry about higher order allocations
> failing with kvmalloc, especially because the xattr size limit is at
> 64K.
So why use vmalloc memory at all?
> diff --git a/fs/xattr.c b/fs/xattr.c
']
> @@ -817,7 +817,7 @@ struct simple_xattr *simple_xattr_alloc(const void *value, size_t size)
> if (len < sizeof(*new_xattr))
> return NULL;
>
> - new_xattr = kmalloc(len, GFP_KERNEL);
> + new_xattr = kvmalloc(len, GFP_KERNEL);
Why is this sensible?
vmalloc memory is a much more limited resource.
Also, it seems as if the function should set
new_xattr->name to NULL before the return.
next prev parent reply other threads:[~2020-03-06 8:51 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-05 21:16 [PATCH v2 0/4] Support user xattrs in cgroupfs Daniel Xu
2020-03-05 21:16 ` [PATCH v2 1/4] kernfs: kvmalloc xattr value instead of kmalloc Daniel Xu
2020-03-06 8:49 ` Joe Perches [this message]
2020-03-06 9:37 ` Greg KH
2020-03-09 18:21 ` Daniel Xu
2020-03-09 19:41 ` Joe Perches
2020-03-09 19:51 ` Tejun Heo
2020-03-09 19:58 ` Joe Perches
2020-03-09 20:05 ` Tejun Heo
2020-03-10 19:40 ` Shakeel Butt
2020-03-10 20:40 ` Daniel Xu
2020-03-10 20:41 ` Shakeel Butt
2020-03-05 21:16 ` [PATCH v2 2/4] kernfs: Add removed_size out param for simple_xattr_set Daniel Xu
2020-03-10 18:20 ` Daniel Xu
2020-03-05 21:16 ` [PATCH v2 3/4] kernfs: Add option to enable user xattrs Daniel Xu
2020-03-05 21:16 ` [PATCH v2 4/4] cgroupfs: Support " Daniel Xu
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