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b=Jg+I5mISszxOM6vxuJLUP7StToWz2ZhNXOYlCHpWWucv2FOMahAAyW9olJkCHsamN rptxT2zcVb5KRr7njgD83lT1mW0XXICmlWbWIlDs9w8Kq3KCrno3ezVryu+wXrD5Ut cMyPy+D+JD+TZIebBf999+FwAyKy2KNsit1+aaVs4qnz7B7dbCUeTmHf1yM3nEiyp7 IOOSC4jJ8ECjGy9cGQ/b3k32jrQ3Lyxc1WOE1/LaesVDBbA2qf6h5NOzHxkL1C0aVD Eu7l0e46W6X6qyeLMYzsCNbNmUMng0duQKijN+C1f9MyeLyCyMSXb9nAoGUrF0bUIa ZvTVD+X7Gz3qw== Date: Sun, 21 Sep 2025 10:39:45 +0300 From: Mike Rapoport To: Ryan Roberts Cc: Dev Jain , akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: Remove PMD alignment constraint in execmem_vmalloc() Message-ID: References: <20250918093453.75676-1-dev.jain@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: CF0E780009 X-Stat-Signature: og8wz4rjj3qmr7fu8egucf4ys4xh844h X-HE-Tag: 1758440392-26468 X-HE-Meta: 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 U/F+pD2+ 0Bzb4bAF7CfKXQ0wA2SarwbbiTTCVL+/VVmd9FRa6wgAqmEuvpsYE0l7M5bueIoFL/NhM62SiSm1cEHEc6BkitIExVmqKIjZffKRxiHt/t9gh+jf0AGNCOZCsQzKFwALBfsc5T3M/o/P7+snes1XF7rs34oqkc0FqqvQov1+p2m11TdWJkQ/0i7+HGbFJPP7TlkE45fvRQHxA7G3NEzWu+hER9qmtqcjU6Gi0jxJXA3chM9IyktPCu7EcoL5si7QC+kgDYELXdByy4vybfi6VwK6lksIGgvZCpqBJotf2WcTa8xoOP9lxl0CtRdibvDtpAUpKsmEV83kLjsMt1n1xuItizLwtgPKMXtJ4K68oqDcHziHdX0EFZiEmXhXiX9YSd2oY 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: Hi Ryan, On Thu, Sep 18, 2025 at 02:06:25PM +0100, Ryan Roberts wrote: > On 18/09/2025 11:33, Mike Rapoport wrote: > > On Thu, Sep 18, 2025 at 03:04:53PM +0530, Dev Jain wrote: > >> When using vmalloc with VM_ALLOW_HUGE_VMAP flag, it will set the alignment > >> to PMD_SIZE internally, if it deems huge mappings to be eligible. > >> Therefore, setting the alignment in execmem_vmalloc is redundant. Apart > >> from this, it also reduces the probability of allocation in case vmalloc > >> fails to allocate hugepages - in the fallback case, vmalloc tries to use > >> the original alignment and allocate basepages, which unfortunately will > >> again be PMD_SIZE passed over from execmem_vmalloc, thus constraining > >> the search for a free space in vmalloc region. > >> > >> Therefore, remove this constraint. > >> > >> Signed-off-by: Dev Jain > > > > Reviewed-by: Mike Rapoport (Microsoft) > > Hijacking this thread to ask Mike a related question, which I noticed during > code review... Replied on the related thread :) https://lore.kernel.org/all/aM-rDD-TRqmtr6Nb@kernel.org/ -- Sincerely yours, Mike.