From: Miaohe Lin <linmiaohe@huawei.com>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: <akpm@linux-foundation.org>, <songmuchun@bytedance.com>,
<linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 3/6] mm/hugetlb: fix missing call to restore_reserve_on_error()
Date: Wed, 17 Aug 2022 09:59:57 +0800 [thread overview]
Message-ID: <14198f4d-f9ff-8e36-d985-3719e365f913@huawei.com> (raw)
In-Reply-To: <YvwovBboCJBOJ1Wm@monkey>
On 2022/8/17 7:31, Mike Kravetz wrote:
> On 08/16/22 21:05, Miaohe Lin wrote:
>> When huge_add_to_page_cache() fails, the page is freed directly without
>> calling restore_reserve_on_error() to restore reserve for newly allocated
>> pages not in page cache. Fix this by calling restore_reserve_on_error()
>> when huge_add_to_page_cache fails.
>>
>> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
>> ---
>> mm/hugetlb.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
>> index ff991e5bdf1f..b69d7808f457 100644
>> --- a/mm/hugetlb.c
>> +++ b/mm/hugetlb.c
>> @@ -5603,6 +5603,7 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
>> if (vma->vm_flags & VM_MAYSHARE) {
>> int err = huge_add_to_page_cache(page, mapping, idx);
>> if (err) {
>> + restore_reserve_on_error(h, vma, haddr, page);
>
> Hmmmm. I was going to comment that restore_reserve_on_error would not handle
> the situation where 'err == -EEXIST' below. This is because it implies we
> raced with someone else that added the page to the cache. And, that other
Thanks for pointing this out.
> allocation, not this one, consumed the reservation. However, I am not sure
> how that could be possible? The hugetlb fault mutex (which we hold)
> must be held to add a page to the page cache.
>
> Searching git history I see that code was added (or at least existed) before
> the hugetlb fault mutex was introduced. So, I believe that check for -EEXIST
> and retry can go.
Agree with you. All call sites of huge_add_to_page_cache is protected by hugetlb fault mutex.
>
> With that said, restore_reserve_on_error can be called here. But, let's
> look into removing that err == -EEXIST check to avoid confusion.
Will do it in next version. Many thanks for your review and comment.
Thanks,
Miaohe Lin
next prev parent reply other threads:[~2022-08-17 2:00 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-16 13:05 [PATCH 0/6] A few fixup patches for hugetlb Miaohe Lin
2022-08-16 13:05 ` [PATCH 1/6] mm/hugetlb: fix incorrect update of max_huge_pages Miaohe Lin
2022-08-16 22:52 ` Mike Kravetz
2022-08-16 23:20 ` Andrew Morton
2022-08-16 23:34 ` Mike Kravetz
2022-08-17 1:53 ` Miaohe Lin
2022-08-17 2:28 ` Muchun Song
2022-08-16 13:05 ` [PATCH 2/6] mm/hugetlb: fix WARN_ON(!kobj) in sysfs_create_group() Miaohe Lin
2022-08-16 22:55 ` Mike Kravetz
2022-08-17 2:31 ` Muchun Song
2022-08-17 2:39 ` Miaohe Lin
2022-08-16 13:05 ` [PATCH 3/6] mm/hugetlb: fix missing call to restore_reserve_on_error() Miaohe Lin
2022-08-16 23:31 ` Mike Kravetz
2022-08-17 1:59 ` Miaohe Lin [this message]
2022-08-16 13:05 ` [PATCH 4/6] mm: hugetlb_vmemmap: add missing smp_wmb() before set_pte_at() Miaohe Lin
2022-08-17 2:53 ` Muchun Song
2022-08-17 8:41 ` Miaohe Lin
2022-08-17 9:13 ` Yin, Fengwei
2022-08-17 11:21 ` Muchun Song
2022-08-18 1:14 ` Yin, Fengwei
2022-08-18 1:55 ` Miaohe Lin
2022-08-18 2:00 ` Yin, Fengwei
2022-08-18 2:47 ` Muchun Song
2022-08-18 7:52 ` Miaohe Lin
2022-08-18 7:59 ` Muchun Song
2022-08-18 8:32 ` Yin, Fengwei
2022-08-18 8:40 ` Muchun Song
2022-08-18 8:54 ` Yin, Fengwei
2022-08-18 9:18 ` Muchun Song
2022-08-18 12:58 ` Miaohe Lin
2022-08-18 23:53 ` Yin, Fengwei
2022-08-19 3:19 ` Muchun Song
2022-08-19 7:26 ` Miaohe Lin
2022-08-18 1:15 ` Yin, Fengwei
2022-08-20 8:12 ` Muchun Song
2022-08-22 8:45 ` Miaohe Lin
2022-08-22 10:23 ` Muchun Song
2022-08-23 1:42 ` Miaohe Lin
2022-08-16 13:05 ` [PATCH 5/6] mm/hugetlb: fix sysfs group leak in hugetlb_unregister_node() Miaohe Lin
2022-08-17 9:41 ` Yin, Fengwei
2022-08-18 1:00 ` Yin, Fengwei
2022-08-18 1:12 ` Yin, Fengwei
2022-08-16 13:05 ` [PATCH 6/6] mm/hugetlb: make detecting shared pte more reliable Miaohe Lin
2022-08-17 23:56 ` Mike Kravetz
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=14198f4d-f9ff-8e36-d985-3719e365f913@huawei.com \
--to=linmiaohe@huawei.com \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mike.kravetz@oracle.com \
--cc=songmuchun@bytedance.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;
as well as URLs for NNTP newsgroup(s).