From: Matthew Wilcox <willy@infradead.org>
To: Greg KH <gregkh@linuxfoundation.org>
Cc: yangerkun <yangerkun@huawei.com>,
stable@vger.kernel.org, vbabka@suse.cz, linux-mm@kvack.org,
open-iscsi@googlegroups.com, cleech@redhat.com,
"zhangyi (F)" <yi.zhang@huawei.com>,
Kefeng Wang <wangkefeng.wang@huawei.com>,
liuyongqiang13@huawei.com,
"Zhengyejian (Zetta)" <zhengyejian1@huawei.com>,
Yang Yingliang <yangyingliang@huawei.com>,
chenzhou10@huawei.com
Subject: Re: [QUESTION] WARNNING after 3d8e2128f26a ("sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output")
Date: Fri, 2 Apr 2021 15:41:20 +0100 [thread overview]
Message-ID: <20210402144120.GO351017@casper.infradead.org> (raw)
In-Reply-To: <YGbLiIL8ewIX1Hrt@kroah.com>
On Fri, Apr 02, 2021 at 09:45:12AM +0200, Greg KH wrote:
> Why is the buffer alignment considered a "waste" here? If that change
> is in Linus's tree and newer kernels (it showed up in 5.4 which was
> released quite a while ago), where are the people complaining about it
> there?
>
> I think backporting 59bb47985c1d ("mm, sl[aou]b: guarantee natural
> alignment for kmalloc(power-of-two)") seems like the correct thing to do
> here to bring things into alignment (pun intended) with newer kernels.
It's only a waste for slabs which need things like redzones (eg we could
get 7 512-byte allocations out of a 4kB page with a 64 byte redzone
and no alignment ; with alignment we can only get four). Since slub
can enable/disable redzones on a per-slab basis, and redzones aren't
terribly interesting now that we have kasan/kfence, nobody really cares.
next prev parent reply other threads:[~2021-04-02 14:42 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-02 7:16 yangerkun
2021-04-02 7:24 ` yangerkun
2021-04-02 7:45 ` Greg KH
2021-04-02 14:41 ` Matthew Wilcox [this message]
2021-04-07 12:14 ` yangerkun
2021-04-07 13:21 ` Joe Perches
2021-04-07 13:49 ` yangerkun
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