From: Baolin Wang <baolin.wang@linux.alibaba.com>
To: Haiyue Wang <haiyue.wang@intel.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: akpm@linux-foundation.org, david@redhat.com, apopple@nvidia.com,
linmiaohe@huawei.com, ying.huang@intel.com,
songmuchun@bytedance.com, naoya.horiguchi@linux.dev,
alex.sierra@amd.com
Subject: Re: [PATCH v6 1/2] mm: migration: fix the FOLL_GET failure on following huge page
Date: Tue, 16 Aug 2022 16:54:53 +0800 [thread overview]
Message-ID: <eb6eb8ff-f0f3-fe6f-feac-887e46593a0e@linux.alibaba.com> (raw)
In-Reply-To: <20220816022102.582865-2-haiyue.wang@intel.com>
On 8/16/2022 10:21 AM, Haiyue Wang wrote:
> Not all huge page APIs support FOLL_GET option, so move_pages() syscall
> will fail to get the page node information for some huge pages.
>
> Like x86 on linux 5.19 with 1GB huge page API follow_huge_pud(), it will
> return NULL page for FOLL_GET when calling move_pages() syscall with the
> NULL 'nodes' parameter, the 'status' parameter has '-2' error in array.
>
> Note: follow_huge_pud() now supports FOLL_GET in linux 6.0.
> Link: https://lore.kernel.org/all/20220714042420.1847125-3-naoya.horiguchi@linux.dev
>
> But these huge page APIs don't support FOLL_GET:
> 1. follow_huge_pud() in arch/s390/mm/hugetlbpage.c
> 2. follow_huge_addr() in arch/ia64/mm/hugetlbpage.c
> It will cause WARN_ON_ONCE for FOLL_GET.
> 3. follow_huge_pgd() in mm/hugetlb.c
>
> This is an temporary solution to mitigate the side effect of the race
> condition fix by calling follow_page() with FOLL_GET set for huge pages.
>
> After supporting follow huge page by FOLL_GET is done, this fix can be
> reverted safely.
>
> Fixes: 4cd614841c06 ("mm: migration: fix possible do_pages_stat_array racing with memory offline")
> Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
> Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
> ---
Looks good to me.
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> mm/migrate.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 6a1597c92261..581dfaad9257 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1848,6 +1848,7 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
>
> for (i = 0; i < nr_pages; i++) {
> unsigned long addr = (unsigned long)(*pages);
> + unsigned int foll_flags = FOLL_DUMP;
> struct vm_area_struct *vma;
> struct page *page;
> int err = -EFAULT;
> @@ -1856,8 +1857,12 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
> if (!vma)
> goto set_status;
>
> + /* Not all huge page follow APIs support 'FOLL_GET' */
> + if (!is_vm_hugetlb_page(vma))
> + foll_flags |= FOLL_GET;
> +
> /* FOLL_DUMP to ignore special (like zero) pages */
> - page = follow_page(vma, addr, FOLL_GET | FOLL_DUMP);
> + page = follow_page(vma, addr, foll_flags);
>
> err = PTR_ERR(page);
> if (IS_ERR(page))
> @@ -1865,7 +1870,8 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
>
> if (page && !is_zone_device_page(page)) {
> err = page_to_nid(page);
> - put_page(page);
> + if (foll_flags & FOLL_GET)
> + put_page(page);
> } else {
> err = -ENOENT;
> }
next prev parent reply other threads:[~2022-08-16 9:54 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-12 8:49 [PATCH v1] mm: migration: fix the FOLL_GET failure on following huge page Haiyue Wang
2022-08-13 23:28 ` Andrew Morton
2022-08-14 6:20 ` Wang, Haiyue
2022-08-14 6:49 ` Wang, Haiyue
2022-08-14 14:05 ` [PATCH v2 0/3] fix follow_page related issues Haiyue Wang
2022-08-14 14:05 ` [PATCH v2 1/3] mm: revert handling Non-LRU pages returned by follow_page Haiyue Wang
2022-08-14 16:30 ` David Hildenbrand
2022-08-15 1:02 ` Wang, Haiyue
2022-08-14 14:05 ` [PATCH v2 2/3] mm: migration: fix the FOLL_GET failure on following huge page Haiyue Wang
2022-08-14 14:05 ` [PATCH v2 3/3] mm: handling Non-LRU pages returned by follow_page Haiyue Wang
2022-08-14 16:34 ` David Hildenbrand
2022-08-15 1:03 ` Wang, Haiyue
2022-08-15 1:03 ` [PATCH v3 0/2] fix follow_page related issues Haiyue Wang
2022-08-15 1:03 ` [PATCH v3 1/2] mm: migration: fix the FOLL_GET failure on following huge page Haiyue Wang
2022-08-15 1:59 ` Huang, Ying
2022-08-15 2:10 ` Wang, Haiyue
2022-08-15 2:15 ` Wang, Haiyue
2022-08-15 2:51 ` Huang, Ying
2022-08-15 1:03 ` [PATCH v3 2/2] mm: fix the handling Non-LRU pages returned by follow_page Haiyue Wang
2022-08-15 1:39 ` Huang, Ying
2022-08-15 1:46 ` Wang, Haiyue
2022-08-15 1:59 ` [PATCH v4 0/2] fix follow_page related issues Haiyue Wang
2022-08-15 1:59 ` [PATCH v4 1/2] mm: migration: fix the FOLL_GET failure on following huge page Haiyue Wang
2022-08-15 4:28 ` Alistair Popple
2022-08-15 4:40 ` Wang, Haiyue
2022-08-15 5:16 ` Alistair Popple
2022-08-15 5:20 ` Wang, Haiyue
2022-08-15 5:35 ` Alistair Popple
2022-08-15 5:37 ` Wang, Haiyue
2022-08-15 1:59 ` [PATCH v4 2/2] mm: fix the handling Non-LRU pages returned by follow_page Haiyue Wang
2022-08-15 7:02 ` [PATCH v5 0/2] fix follow_page related issues Haiyue Wang
2022-08-15 7:02 ` [PATCH v5 1/2] mm: migration: fix the FOLL_GET failure on following huge page Haiyue Wang
2022-08-15 7:40 ` Huang, Ying
2022-08-15 7:02 ` [PATCH v5 2/2] mm: fix the handling Non-LRU pages returned by follow_page Haiyue Wang
2022-08-15 7:50 ` Huang, Ying
2022-08-15 14:28 ` Felix Kuehling
2022-08-16 0:00 ` Alistair Popple
2022-08-16 1:12 ` Wang, Haiyue
2022-08-16 2:45 ` Alistair Popple
2022-08-16 2:20 ` [PATCH v6 0/2] fix follow_page related issues Haiyue Wang
2022-08-16 2:21 ` [PATCH v6 1/2] mm: migration: fix the FOLL_GET failure on following huge page Haiyue Wang
2022-08-16 8:54 ` Baolin Wang [this message]
2022-08-17 0:58 ` Andrew Morton
2022-08-17 3:31 ` Wang, Haiyue
2022-08-17 5:43 ` Andrew Morton
2022-08-17 5:47 ` Wang, Haiyue
2022-08-17 17:26 ` Mike Kravetz
2022-08-17 21:58 ` Mike Kravetz
2022-08-18 0:32 ` Wang, Haiyue
2022-08-19 11:22 ` Michael Ellerman
2022-08-19 16:55 ` Mike Kravetz
2022-08-26 13:07 ` Michael Ellerman
2022-08-18 11:51 ` Gerald Schaefer
2022-08-18 11:57 ` Gerald Schaefer
2022-08-17 2:12 ` Miaohe Lin
2022-08-16 2:21 ` [PATCH v6 2/2] mm: fix the handling Non-LRU pages returned by follow_page Haiyue Wang
2022-08-16 4:42 ` Alistair Popple
2022-08-17 2:34 ` Miaohe Lin
2022-08-23 10:07 ` David Hildenbrand
2022-08-23 13:26 ` Wang, Haiyue
2022-08-23 13:27 ` David Hildenbrand
2022-08-23 13:29 ` Wang, Haiyue
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