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Fri, 21 Jun 2024 20:03:13 -0700 (PDT) Received: from localhost.localdomain ([2407:7000:8942:5500:aaa1:59ff:fe57:eb97]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-70651254c67sm2196086b3a.97.2024.06.21.20.03.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Jun 2024 20:03:12 -0700 (PDT) From: Barry Song <21cnbao@gmail.com> To: akpm@linux-foundation.org Cc: baolin.wang@linux.alibaba.com, chrisl@kernel.org, david@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, mhocko@suse.com, ryan.roberts@arm.com, shy828301@gmail.com, surenb@google.com, v-songbaohua@oppo.com, willy@infradead.org, ying.huang@intel.com, yosryahmed@google.com, yuanshuai@oppo.com, yuzhao@google.com Subject: Re: [PATCH v2 1/3] mm: extend rmap flags arguments for folio_add_new_anon_rmap Date: Sat, 22 Jun 2024 15:02:56 +1200 Message-Id: <20240622030256.43775-1-21cnbao@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240617231137.80726-2-21cnbao@gmail.com> References: <20240617231137.80726-2-21cnbao@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 99E43A0007 X-Stat-Signature: 6ewktr6gxunge5hxfcrm8eks4p46c3w7 X-Rspam-User: X-HE-Tag: 1719025394-726850 X-HE-Meta: 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 0fATsWUS 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > > From: Barry Song > > In the case of a swap-in, a new anonymous folio is not necessarily > exclusive. This patch updates the rmap flags to allow a new anonymous > folio to be treated as either exclusive or non-exclusive. To maintain > the existing behavior, we always use EXCLUSIVE as the default setting. > > Suggested-by: David Hildenbrand > Signed-off-by: Barry Song > Tested-by: Shuai Yuan > --- Hi Andrew, Could you please help squash the following change (a documentation enhancement suggested by David) into this patch? From: Barry Song Date: Sat, 22 Jun 2024 14:51:38 +1200 Subject: [PATCH] mm: enhence doc for extend rmap flags arguments for folio_add_new_anon_rmap Suggested-by: David Hildenbrand Signed-off-by: Barry Song --- mm/rmap.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/mm/rmap.c b/mm/rmap.c index df1a43295c85..9a8d9c848168 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -1394,7 +1394,9 @@ void folio_add_anon_rmap_pmd(struct folio *folio, struct page *page, * * Like folio_add_anon_rmap_*() but must only be called on *new* folios. * This means the inc-and-test can be bypassed. - * The folio does not have to be locked. + * The folio doesn't necessarily need to be locked while it's exclusive + * unless two threads map it concurrently. However, the folio must be + * locked if it's shared. * * If the folio is pmd-mappable, it is accounted as a THP. */ @@ -1406,6 +1408,7 @@ void folio_add_new_anon_rmap(struct folio *folio, struct vm_area_struct *vma, int nr_pmdmapped = 0; VM_WARN_ON_FOLIO(folio_test_hugetlb(folio), folio); + VM_WARN_ON_FOLIO(!exclusive && !folio_test_locked(folio), folio); VM_BUG_ON_VMA(address < vma->vm_start || address + (nr << PAGE_SHIFT) > vma->vm_end, vma); __folio_set_swapbacked(folio); -- 2.34.1