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[2003:cb:c700:fc00:490d:ed6a:8b22:223a]) by smtp.gmail.com with ESMTPSA id y9-20020a05600015c900b0020adb0e106asm2756818wry.93.2022.04.25.00.39.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 25 Apr 2022 00:39:10 -0700 (PDT) Message-ID: Date: Mon, 25 Apr 2022 09:39:09 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.6.2 Subject: Re: [PATCH v3 2/3] mm/swapfile: Fix lost swap bits in unuse_pte() Content-Language: en-US To: Miaohe Lin , akpm@linux-foundation.org Cc: willy@infradead.org, vbabka@suse.cz, dhowells@redhat.com, neilb@suse.de, apopple@nvidia.com, surenb@google.com, minchan@kernel.org, peterx@redhat.com, sfr@canb.auug.org.au, naoya.horiguchi@nec.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20220424091105.48374-1-linmiaohe@huawei.com> <20220424091105.48374-3-linmiaohe@huawei.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20220424091105.48374-3-linmiaohe@huawei.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24.04.22 11:11, Miaohe Lin wrote: > This is observed by code review only but not any real report. > > When we turn off swapping we could have lost the bits stored in the swap > ptes. The new rmap-exclusive bit is fine since that turned into a page > flag, but not for soft-dirty and uffd-wp. Add them. > > Suggested-by: Peter Xu > Signed-off-by: Miaohe Lin > --- > mm/swapfile.c | 10 +++++++--- > 1 file changed, 7 insertions(+), 3 deletions(-) > > diff --git a/mm/swapfile.c b/mm/swapfile.c > index 95b63f69f388..522a0eb16bf1 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -1783,7 +1783,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, > { > struct page *swapcache; > spinlock_t *ptl; > - pte_t *pte; > + pte_t *pte, new_pte; > int ret = 1; > > swapcache = page; > @@ -1832,8 +1832,12 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, > page_add_new_anon_rmap(page, vma, addr); > lru_cache_add_inactive_or_unevictable(page, vma); > } > - set_pte_at(vma->vm_mm, addr, pte, > - pte_mkold(mk_pte(page, vma->vm_page_prot))); > + new_pte = pte_mkold(mk_pte(page, vma->vm_page_prot)); > + if (pte_swp_soft_dirty(*pte)) > + new_pte = pte_mksoft_dirty(new_pte); > + if (pte_swp_uffd_wp(*pte)) > + new_pte = pte_mkuffd_wp(new_pte); > + set_pte_at(vma->vm_mm, addr, pte, new_pte); > swap_free(entry); > out: > pte_unmap_unlock(pte, ptl); Reviewed-by: David Hildenbrand -- Thanks, David / dhildenb