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b=vJEETtdddAlz7+EIMGm4DFsoK2J4nhFAUDgu3sHei+wYslXrtYTuv0lfjA0KOc7+L MwOHC1I9bfN82KG/UdpfdjP4uSeUx+hjAphiy6+RoyU2R2IFNSs7V2RFgeYVnV1WiG 3T4GGcwtZYgqkZHsFtD92xJe+vpDNX8rNcdU4WyI= Date: Wed, 15 Jul 2026 11:58:52 -0700 From: Andrew Morton To: Dev Jain Cc: david@kernel.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, kasong@tencent.com, qi.zheng@linux.dev, shakeel.butt@linux.dev, baohua@kernel.org, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, riel@surriel.com, harry@kernel.org, jannh@google.com, lance.yang@linux.dev, ryan.roberts@arm.com, anshuman.khandual@arm.com Subject: Re: [PATCH 0/3] Batch unmap of uffd-wp file folios Message-Id: <20260715115852.a32e472d97fa182d6a5ee482@linux-foundation.org> In-Reply-To: <20260715111839.1667914-1-dev.jain@arm.com> References: <20260715111839.1667914-1-dev.jain@arm.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam09 X-Rspamd-Queue-Id: 96C464000A X-Stat-Signature: r3ttiid5er8trxj13fuih63h8p8744xb X-HE-Tag: 1784141934-904877 X-HE-Meta: U2FsdGVkX1+z3G+WJMrajroipN+AR//1SdUqTjx2YuNGZ3rKYveR94uCkz+fD3YKjNu3uNvpF7XXLv+BRfu8rY8frJWJYZQtW+h+iXzPzqGEjgnXMrW0VJc0YFhZoCyuHSNCLAceTbT76AO/pjb464zCVnOwehZpUMd4k4iTAAxmlJFb3qddOEQ7vtAAPBzY8yQl9xOOmpg/joTDKZlICAonCu2y5z8eBlDUjFmrG/Szw2yxTUv15c7835jcsQhbEBsipsOrZ2OrmtZvbYwZyiZP0/oulq9LFMyzmGJ37S/doQiXKslwzofjoMKJEeE8sieGeUWAAL0rAooQoov5APeait5EG0u+LuqXyfaSwWvTzxC17vnR2AgAmlPwRE41AKn5I/Si1DSSxmkncGDG7eeqZrOmetdXywDoT0Pt0pnG8jJH+QWLnIhc0ND+OwMHhdL8w+Fk0jJRKqD//zLTNTKxkiOiysIbsvr2c/ilTbLCWL3jvvnd+tcS7hS1FkCZkErYkxVVqHWP83lGZFLFn4nPcPb8IxG19z+QFCetckVFTNucjAo8b6pA37NyHnd8IcRGGhGij3ZtnmUcZGBYZABNwf2JVIpwoX4X+JFgsCEpK4uc1R1++URBDnQdP6B4Ip93DNy0v8v2GI4+apAHYL+hxMhjQ+o9bOI66Mv80qf/iFuHngmxRNBS1vBumcgp87eAC0v2/WcAr2tb1bt6t3HCQu5NqK8VpNVM0PSt7qJ9Kt3/ido6TWFxrCcp3l8Z3LZabpPv1/MpZdDaKLU+KZu5phLZPlH8U8Rk4feOTVeGlH6frZQQi5zd6gipi72TfUea3s3ELdeOJQlzzzgZmOUrsAjcIEiB3ZBnGdrwFjQgSFyy9ca0mdnsSC1ueL2fHmi0Tp2lllXmyMU36swBLka8TDd5n1L56ay8sBGq6M/xbWM8oAYDFj3lreiBhqbbinQvPFMHkXrOV7Epgx4 si29Lseb GckpXhqhrvhllCI3FU+cD++tVrlwE/QFnO9bjJRQMNIrnEX45aTpF2bTDhWERCzIaBdxfHeYdKzUwWaBq7Bf7cLK8+Hrt5hXDI9u4kkWAkCptdbcmXxiGHVyHQRCRfv5rzuChr9b3TvvpELQSCJFaWqJmHJsgU1xhQdkQsSiBSvKVpOM3hlEz4SDJJ3vb+o9CBOU7uJA2nEpbdvB/6m4cf6PCpJjd9kf1x19PUIQHLwmyY2VX1Y0neycdCZevBKSMX0lxZuZQnXRtazFhp56fhRCr3W9jnED031GBhrcxdd+hAcyZXFJqEoYg7Q5kYOadGysGxgE6E+IO/KXrvAPrUjzzswQ1brnVC20U2ACzHcAdDI6v9QIntcC/2w== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 15 Jul 2026 11:18:33 +0000 Dev Jain wrote: > Currently, batched unmapping is supported if: > > 1) folio is a file folio, not belonging to uffd-wp VMA > 2) folio is anonymous and not swapbacked (lazyfree), not belonging to > uffd-wp VMA > > So the cases which are not supported are > > 1) folio belonging to uffd-wp VMA > 2) folio is anonymous and swapbacked > > It is easy to see that this adds a lot of cognitive load while reading > try_to_unmap_one - we need to remember throughout whether nr_pages == 1 > or > 1. > > The uffd-wp handling in try_to_unmap_one is regarding preserving the > uffd-wp state for file folios via pte_install_uffd_wp_if_needed (for anon > folio, we handle that while constructing the swap pte). > > Stop special casing on uffd-wp VMAs by simply adding batching support > to pte_install_uffd_wp_if_needed. Thanks, I'll await reviewer input on this. Sashiko might have found a pre-existing issue: https://sashiko.dev/#/patchset/20260715111839.1667914-1-dev.jain@arm.com