From: David Hildenbrand <david@redhat.com>
To: jane.chu@oracle.com, Liu Shixin <liushixin2@huawei.com>,
Andrew Morton <akpm@linux-foundation.org>,
Muchun Song <muchun.song@linux.dev>,
Kenneth W Chen <kenneth.w.chen@intel.com>,
Kefeng Wang <wangkefeng.wang@huawei.com>,
Nanyong Sun <sunnanyong@huawei.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: hugetlb: independent PMD page table shared count
Date: Tue, 17 Dec 2024 12:55:32 +0100 [thread overview]
Message-ID: <c9e45248-089e-4041-8f7e-98203a0831cf@redhat.com> (raw)
In-Reply-To: <a4e938ec-ed63-41bf-8c5b-a3697a0fea04@oracle.com>
On 16.12.24 19:33, jane.chu@oracle.com wrote:
> On 12/14/2024 2:44 AM, Liu Shixin wrote:
>
>> The folio refcount may be increased unexpectly through try_get_folio() by
>> caller such as split_huge_pages. In huge_pmd_unshare(), we use refcount to
>> check whether a pmd page table is shared. The check is incorrect if the
>> refcount is increased by the above caller, and this can cause the page
>> table leaked:
>
> hugetlb and THP don't overlap, right? how does split_huge_pages() end
> up messing up huge_pmd_share() ?
>
> Am I missing something?
>
If first grabs a reference to then check if it's a THP. So we can end up
grabbing anything temporarily.
In general, we'll have to be smarter about what we try grabbing, but
handling races for now is tricky.
--
Cheers,
David / dhildenb
prev parent reply other threads:[~2024-12-17 11:55 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-12-14 10:44 Liu Shixin
2024-12-15 5:11 ` kernel test robot
2024-12-15 5:11 ` kernel test robot
2024-12-15 7:45 ` kernel test robot
2024-12-16 15:34 ` David Hildenbrand
2024-12-17 2:02 ` Liu Shixin
2024-12-17 11:56 ` David Hildenbrand
2024-12-16 18:33 ` jane.chu
2024-12-17 11:55 ` David Hildenbrand [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=c9e45248-089e-4041-8f7e-98203a0831cf@redhat.com \
--to=david@redhat.com \
--cc=akpm@linux-foundation.org \
--cc=jane.chu@oracle.com \
--cc=kenneth.w.chen@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=liushixin2@huawei.com \
--cc=muchun.song@linux.dev \
--cc=sunnanyong@huawei.com \
--cc=wangkefeng.wang@huawei.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox