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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20251003155306.2147572-1-ryan.roberts@arm.com> From: Baolin Wang In-Reply-To: <20251003155306.2147572-1-ryan.roberts@arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 66A9E1C000A X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: pc87i8tiecsmqnzcwpta1ztupn18ftke X-HE-Tag: 1760407677-847836 X-HE-Meta: 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 ncqqpkO5 /CpKuJGzsnycuQSsGv0u9OEnZJN/96j04Kgvu5dkXzJWFgfLvwTPxu4sVhmMMb/buIzZmFIUlW9FZlLTQLWOZAc9xVczyk90wovk+O4cEjEGw5XPpCJ9OMpHacr/pM0VR6SNxSZNzi8L6kcJtvAn0b6uDSq+0oA7ToaQCN1vj6/7QWNWoc9PSreBvncpwX5p0vvHa0e72pMI4U4Vglj26SZPA15ketS7ggOIMiBb/efifv2+CUyX39cvRBkLpTbI3OPLGIwtGLAAP6U54vNQAlK3EyIZY7Y3TU73VeKuTDMN7Oibag6fC/3xOO9IsFv24nUUFfSlwWX9uYQHBn+eQHXlQmLRiR8GErSoy+ZZhrULxkUXM9Z4rBBS4+5Qdoub4al4CHa4w6aJ3937Bawelgyji3rlSoJEqD40r47TQxB58hyhXzK1s896u4g== 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 2025/10/3 23:53, Ryan Roberts wrote: > mm_get_unmapped_area() is a wrapper around arch_get_unmapped_area() / > arch_get_unmapped_area_topdown(), both of which search current->mm for > some free space. Neither take an mm_struct - they implicitly operate on > current->mm. > > But the wrapper takes an mm_struct and uses it to decide whether to > search bottom up or top down. All callers pass in current->mm for this, > so everything is working consistently. But it feels like an accident > waiting to happen; eventually someone will call that function with a > different mm, expecting to find free space in it, but what gets returned > is free space in the current mm. > > So let's simplify by removing the parameter and have the wrapper use > current->mm to decide which end to start at. Now everything is > consistent and self-documenting. > > Signed-off-by: Ryan Roberts > --- Nice cleanup. LGTM. Reviewed-by: Baolin Wang