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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1ux5aQ-00000000rLL-0XaV; Fri, 12 Sep 2025 15:21:18 +0000 Date: Fri, 12 Sep 2025 16:21:17 +0100 From: Matthew Wilcox To: Baolin Wang Cc: akpm@linux-foundation.org, hannes@cmpxchg.org, david@redhat.com, mhocko@kernel.org, zhengqi.arch@bytedance.com, shakeel.butt@linux.dev, lorenzo.stoakes@oracle.com, hughd@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] mm: vmscan: remove folio_test_private() check in pageout() Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 306D9C000A X-Stat-Signature: 4dqjmw8yqieah8y4xd8jx4i6eg3ggq4t X-HE-Tag: 1757690491-919097 X-HE-Meta: U2FsdGVkX19SmkK+KkWw218tNM7JYl7C6yEctHLsB74o43SS64Oe9z1xRjbTtfc0ewo+vtoXsOBV6a8XVVUviKO3PSZXo7eg58QCpxEz6mTByg3FP2eEQzydLJHtRdHcoRFPo5+jpUNSggeIF9Lrn3l/ShfHXELnc7HrfBLxpe3c0UFVV379/X0R7Ucz6rIQH+ar8sNtN3hNeNDuYNplJZ1uYtjLGfe5XaEs+sG6clswp0Hqiwq/0wbavNIiF93iBsVolkiMx0E+FTw1i4rXfgXNAQSvEzcECE59/u1aTeOOzYjzkfKIfK0si4dWFGu/HT8JWeJu5JjNn6dMH1pDDgpHFi6LxlpZOt3al6hr3JZFCWBoqYx7YlrJQjY2CxXJeZO2gnC0V9pBwZEtSxb2g55Dpk335JyB6ISyUG5bm7vBiSCud+eZ7+1pI8ppHPsf7oT3lSMxZzupkiXSWyRaQet/kZQa0ijPWtk9blru2qZXvKfiKbCVKCpvJjxwroJXM6rdiMPjMWiEGQYybR9raFDgha6Nzz+To6QWkTZDihD1Zw6QDwK5HeOML0SJ43IODOn6qCc/qJifhkvvY1BMbOCF3hs9k9z/ozGqt0ska/vgYYnNBNpUmqFGyVLKF4Evv944wmbr70o3jEo7cERpbkpS6Wv+s2aOz/2u6aM73nqgE5KCK2v1HisD4+C08qr117eBIep/G3dHxcpQd/rOt3G+a8mGaleTF0eYunoliLHaZKBzji96lK6IgKM2r3lip9TySEpSol98F1Z5jhQ50+YlR0NZuZXYFP/LFyLTGDaj663iUHNjpFs1k+XYydKmiv5gf47J75/AFym6F8G5+tRBru5F+upYghPqu3HhnRUjrYdrGuGl6E2DWB6WOlZiSNLE1upwW+ylbIxMeUgQgWr8KDxDo+AhPv7fjXMDd0FCHiprLYWg7Hoc2jppPlXT9O7IjU+cDR62blcvsxb ww2YExX0 WQweZn1Bvf/ir55/D83+h+blBL3T9kLnqMRBsdKVThoydS8uAo5nzmjVnBeTyhhj1tJ4Ru5nxwb0tW3vFx+zaQYy+BSiyzdzfIYb9ShSsbc8jKzA2+EFBaCCAyZcBOiGHD9gCtl8MsebTQB1VK6K1xmq95cJfAwIut2Vc/Cdh6uXmta16OaOk0Cw8sKVl8U5FU24yKsrIhNaH195W6lEYoFeaw5/N3Vynbb3I 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: On Fri, Sep 12, 2025 at 11:45:07AM +0800, Baolin Wang wrote: > @@ -697,22 +697,8 @@ static pageout_t pageout(struct folio *folio, struct address_space *mapping, > * swap_backing_dev_info is bust: it doesn't reflect the > * congestion state of the swapdevs. Easy to fix, if needed. > */ > - if (!is_page_cache_freeable(folio)) > + if (!is_page_cache_freeable(folio) || !mapping) > return PAGE_KEEP; I feel like we need to keep the comment (assuming it's still true ... which it probably is, although there's nobody who would think to update this comment if it became no longer true). I would certainly wonder why we can have this !mapping test. > - /* > - * Some data journaling orphaned folios can have > - * folio->mapping == NULL while being dirty with clean buffers. > - */ I approve of this simplification, and I think there's more work to be done in this area. Thanks for doing it.