From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Miaohe Lin <linmiaohe@huawei.com>
Cc: akpm@linux-foundation.org, shy828301@gmail.com,
willy@infradead.org, zokeefe@google.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 02/16] mm/huge_memory: access vm_page_prot with READ_ONCE in remove_migration_pmd
Date: Thu, 23 Jun 2022 06:14:01 +0300 [thread overview]
Message-ID: <20220623031401.wdyt5ylin4aijzhh@box.shutemov.name> (raw)
In-Reply-To: <20220622170627.19786-3-linmiaohe@huawei.com>
On Thu, Jun 23, 2022 at 01:06:13AM +0800, Miaohe Lin wrote:
> vma->vm_page_prot is read lockless from the rmap_walk, it may be updated
> concurrently. Using READ_ONCE to prevent the risk of reading intermediate
> values.
Have you checked all other vm_page_prot reads that they hold mmap_lock?
I think the right fix would be to provide a helper to read vm_page_prot
which does READ_ONCE() and use it everywhere. This seems more sustainable.
--
Kirill A. Shutemov
next prev parent reply other threads:[~2022-06-23 3:11 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-22 17:06 [PATCH 00/16] A few cleanup patches for huge_memory Miaohe Lin
2022-06-22 17:06 ` [PATCH 01/16] mm/huge_memory: use flush_pmd_tlb_range in move_huge_pmd Miaohe Lin
2022-06-23 6:30 ` Muchun Song
2022-06-24 18:32 ` Zach O'Keefe
2022-06-22 17:06 ` [PATCH 02/16] mm/huge_memory: access vm_page_prot with READ_ONCE in remove_migration_pmd Miaohe Lin
2022-06-23 3:14 ` Kirill A. Shutemov [this message]
2022-06-23 12:03 ` Miaohe Lin
2022-06-24 18:40 ` Zach O'Keefe
2022-06-25 3:17 ` Miaohe Lin
2022-06-22 17:06 ` [PATCH 03/16] mm/huge_memory: fix comment of __pud_trans_huge_lock Miaohe Lin
2022-06-23 6:32 ` Muchun Song
2022-06-24 18:47 ` Zach O'Keefe
2022-06-25 3:33 ` Miaohe Lin
2022-06-24 18:56 ` Matthew Wilcox
2022-06-25 3:32 ` Miaohe Lin
2022-06-22 17:06 ` [PATCH 04/16] mm/huge_memory: use helper touch_pud in huge_pud_set_accessed Miaohe Lin
2022-06-23 6:42 ` Muchun Song
2022-06-23 12:08 ` Miaohe Lin
2022-06-22 17:06 ` [PATCH 05/16] mm/huge_memory: use helper touch_pmd in huge_pmd_set_accessed Miaohe Lin
2022-06-23 6:43 ` Muchun Song
2022-06-22 17:06 ` [PATCH 06/16] mm/huge_memory: rename mmun_start to haddr in remove_migration_pmd Miaohe Lin
2022-06-23 6:46 ` Muchun Song
2022-06-22 17:06 ` [PATCH 07/16] mm/huge_memory: minor cleanup for split_huge_pages_pid Miaohe Lin
2022-06-23 3:22 ` Kirill A. Shutemov
2022-06-23 12:07 ` Miaohe Lin
2022-06-22 17:06 ` [PATCH 08/16] mm/huge_memory: use helper macro __ATTR_RW Miaohe Lin
2022-06-23 6:49 ` Muchun Song
2022-06-22 17:06 ` [PATCH 09/16] mm/huge_memory: fix comment in zap_huge_pud Miaohe Lin
2022-06-22 17:06 ` [PATCH 10/16] mm/huge_memory: check pmd_present first in is_huge_zero_pmd Miaohe Lin
2022-06-23 6:59 ` Muchun Song
2022-06-22 17:06 ` [PATCH 11/16] mm/huge_memory: try to free subpage in swapcache when possible Miaohe Lin
2022-06-22 17:06 ` [PATCH 12/16] mm/huge_memory: minor cleanup for split_huge_pages_all Miaohe Lin
2022-06-22 17:06 ` [PATCH 13/16] mm/huge_memory: add helper __get_deferred_split_queue Miaohe Lin
2022-06-23 7:03 ` Muchun Song
2022-06-23 12:11 ` Miaohe Lin
2022-06-22 17:06 ` [PATCH 14/16] mm/huge_memory: fix comment of page_deferred_list Miaohe Lin
2022-06-23 7:24 ` Muchun Song
2022-06-23 12:26 ` Miaohe Lin
2022-06-24 17:09 ` Zach O'Keefe
2022-06-25 3:18 ` Miaohe Lin
2022-06-22 17:06 ` [PATCH 15/16] mm/huge_memory: correct comment of prep_transhuge_page Miaohe Lin
2022-06-23 7:26 ` Muchun Song
2022-06-22 17:06 ` [PATCH 16/16] mm/huge_memory: comment the subtle logic in __split_huge_pmd Miaohe Lin
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