From: Matthew Wilcox <willy@infradead.org>
To: David Hildenbrand <david@redhat.com>
Cc: linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
David Rientjes <rientjes@google.com>,
Shakeel Butt <shakeelb@google.com>,
John Hubbard <jhubbard@nvidia.com>,
Jason Gunthorpe <jgg@nvidia.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Mike Rapoport <rppt@linux.ibm.com>,
Yang Shi <shy828301@gmail.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Vlastimil Babka <vbabka@suse.cz>, Jann Horn <jannh@google.com>,
Michal Hocko <mhocko@kernel.org>, Nadav Amit <namit@vmware.com>,
Rik van Riel <riel@surriel.com>, Roman Gushchin <guro@fb.com>,
Andrea Arcangeli <aarcange@redhat.com>,
Peter Xu <peterx@redhat.com>, Donald Dutile <ddutile@redhat.com>,
Christoph Hellwig <hch@lst.de>, Oleg Nesterov <oleg@redhat.com>,
Jan Kara <jack@suse.cz>, Liang Zhang <zhangliang5@huawei.com>,
linux-mm@kvack.org
Subject: Re: [PATCH RFC v2 2/9] mm: optimize do_wp_page() for fresh pages in local LRU pagevecs
Date: Wed, 26 Jan 2022 14:31:23 +0000 [thread overview]
Message-ID: <YfFbOypqMjkeNA3q@casper.infradead.org> (raw)
In-Reply-To: <20220126095557.32392-3-david@redhat.com>
On Wed, Jan 26, 2022 at 10:55:50AM +0100, David Hildenbrand wrote:
> diff --git a/mm/memory.c b/mm/memory.c
> index bcd3b7c50891..61d67ceef734 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -3298,7 +3298,17 @@ static vm_fault_t do_wp_page(struct vm_fault *vmf)
> *
> * PageKsm() doesn't necessarily raise the page refcount.
> */
> - if (PageKsm(page) || page_count(page) > 1 + PageSwapCache(page))
> + if (PageKsm(page))
> + goto copy;
> + if (page_count(page) > 1 + PageSwapCache(page) + !PageLRU(page))
> + goto copy;
> + if (!PageLRU(page))
> + /*
> + * Note: We cannot easily detect+handle references from
> + * remote LRU pagevecs or references to PageLRU() pages.
> + */
> + lru_add_drain();
> + if (page_count(page) > 1 + PageSwapCache(page))
> goto copy;
I worry we're starting to get too accurate here. How about:
if (PageKsm(page) || page_count(page) > 3)
goto copy;
if (!PageLRU(page))
lru_add_drain();
if (!trylock_page(page))
goto copy;
...
> if (!trylock_page(page))
> goto copy;
> --
> 2.34.1
>
next prev parent reply other threads:[~2022-01-26 14:31 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-26 9:55 [PATCH RFC v2 0/9] mm: COW fixes part 1: fix the COW security issue for THP and swap David Hildenbrand
2022-01-26 9:55 ` [PATCH RFC v2 1/9] mm: optimize do_wp_page() for exclusive pages in the swapcache David Hildenbrand
2022-01-26 14:25 ` Matthew Wilcox
2022-01-28 12:53 ` Vlastimil Babka
2022-01-28 13:44 ` David Hildenbrand
2022-01-26 9:55 ` [PATCH RFC v2 2/9] mm: optimize do_wp_page() for fresh pages in local LRU pagevecs David Hildenbrand
2022-01-26 14:31 ` Matthew Wilcox [this message]
2022-01-26 14:36 ` David Hildenbrand
2022-01-26 9:55 ` [PATCH RFC v2 3/9] mm: slightly clarify KSM logic in do_swap_page() David Hildenbrand
2022-01-26 9:55 ` [PATCH RFC v2 4/9] mm: streamline COW " David Hildenbrand
2022-01-26 9:55 ` [PATCH RFC v2 5/9] mm/huge_memory: streamline COW logic in do_huge_pmd_wp_page() David Hildenbrand
2022-01-26 20:36 ` Yang Shi
2022-01-27 8:14 ` David Hildenbrand
2022-01-26 9:55 ` [PATCH RFC v2 6/9] mm/khugepaged: remove reuse_swap_page() usage David Hildenbrand
2022-01-27 21:23 ` Yang Shi
2022-01-28 8:41 ` David Hildenbrand
2022-01-28 17:10 ` Yang Shi
2022-01-26 9:55 ` [PATCH RFC v2 7/9] mm/swapfile: remove reuse_swap_page() David Hildenbrand
2022-01-26 9:55 ` [PATCH RFC v2 8/9] mm/huge_memory: remove stale page_trans_huge_mapcount() David Hildenbrand
2022-01-26 9:55 ` [PATCH RFC v2 9/9] mm/huge_memory: remove stale locking logic from __split_huge_pmd() David Hildenbrand
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