From: Matthew Wilcox <willy@infradead.org>
To: "Vishal Moola (Oracle)" <vishal.moola@gmail.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org,
Hugh Dickins <hughd@google.com>, Peter Xu <peterx@redhat.com>
Subject: Re: [PATCH 3/5] userfualtfd: Replace lru_cache functions with folio_add functions
Date: Tue, 1 Nov 2022 18:31:26 +0000 [thread overview]
Message-ID: <Y2Fl/pZyLSw/ddZY@casper.infradead.org> (raw)
In-Reply-To: <20221101175326.13265-4-vishal.moola@gmail.com>
On Tue, Nov 01, 2022 at 10:53:24AM -0700, Vishal Moola (Oracle) wrote:
> Replaces lru_cache_add() and lru_cache_add_inactive_or_unevictable()
> with folio_add_lru() and folio_add_lru_vma(). This is in preparation for
> the removal of lru_cache_add().
Ummmmm. Reviewing this patch reveals a bug (not introduced by your
patch). Look:
mfill_atomic_install_pte:
bool page_in_cache = page->mapping;
mcontinue_atomic_pte:
ret = shmem_get_folio(inode, pgoff, &folio, SGP_NOALLOC);
...
page = folio_file_page(folio, pgoff);
ret = mfill_atomic_install_pte(dst_mm, dst_pmd, dst_vma, dst_addr,
page, false, wp_copy);
That says pretty plainly that mfill_atomic_install_pte() can be passed
a tail page from shmem, and if it is ...
if (page_in_cache) {
...
} else {
page_add_new_anon_rmap(page, dst_vma, dst_addr);
lru_cache_add_inactive_or_unevictable(page, dst_vma);
}
it'll get put on the rmap as an anon page!
> Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
> ---
> mm/userfaultfd.c | 6 ++++--
> 1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c
> index e24e8a47ce8a..2560973b00d8 100644
> --- a/mm/userfaultfd.c
> +++ b/mm/userfaultfd.c
> @@ -66,6 +66,7 @@ int mfill_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd,
> bool vm_shared = dst_vma->vm_flags & VM_SHARED;
> bool page_in_cache = page->mapping;
> spinlock_t *ptl;
> + struct folio *folio;
> struct inode *inode;
> pgoff_t offset, max_off;
>
> @@ -113,14 +114,15 @@ int mfill_atomic_install_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd,
> if (!pte_none_mostly(*dst_pte))
> goto out_unlock;
>
> + folio = page_folio(page);
> if (page_in_cache) {
> /* Usually, cache pages are already added to LRU */
> if (newly_allocated)
> - lru_cache_add(page);
> + folio_add_lru(folio);
> page_add_file_rmap(page, dst_vma, false);
> } else {
> page_add_new_anon_rmap(page, dst_vma, dst_addr);
> - lru_cache_add_inactive_or_unevictable(page, dst_vma);
> + folio_add_lru_vma(folio, dst_vma);
> }
>
> /*
> --
> 2.38.1
>
>
next prev parent reply other threads:[~2022-11-01 18:31 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-01 17:53 [PATCH 0/5] Removing the lru_cache_add() wrapper Vishal Moola (Oracle)
2022-11-01 17:53 ` [PATCH 1/5] filemap: Convert replace_page_cache_page() to replace_page_cache_folio() Vishal Moola (Oracle)
2022-11-01 18:20 ` Matthew Wilcox
2022-11-01 17:53 ` [PATCH 2/5] fuse: Convert fuse_try_move_page() to use folios Vishal Moola (Oracle)
2022-11-01 18:24 ` Matthew Wilcox
2022-11-10 18:36 ` Vishal Moola
2022-11-14 13:25 ` Miklos Szeredi
2022-11-01 17:53 ` [PATCH 3/5] userfualtfd: Replace lru_cache functions with folio_add functions Vishal Moola (Oracle)
2022-11-01 18:31 ` Matthew Wilcox [this message]
2022-11-02 19:02 ` Peter Xu
2022-11-02 19:21 ` Matthew Wilcox
2022-11-02 20:44 ` Peter Xu
2022-11-03 17:34 ` Axel Rasmussen
2022-11-03 17:56 ` Peter Xu
2022-11-02 20:47 ` Andrew Morton
2022-11-01 17:53 ` [PATCH 4/5] khugepage: Replace lru_cache_add() with folio_add_lru() Vishal Moola (Oracle)
2022-11-01 18:32 ` Matthew Wilcox
2022-11-01 17:53 ` [PATCH 5/5] folio-compat: Remove lru_cache_add() Vishal Moola (Oracle)
2022-11-01 18:33 ` Matthew Wilcox
2022-11-29 19:25 ` [PATCH 0/5] Removing the lru_cache_add() wrapper Vishal Moola
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