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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 5358940004 X-Stat-Signature: esaqmd8fp4uz18zekkk3szc74x1krbp1 X-Rspam-User: X-HE-Tag: 1759811634-344128 X-HE-Meta: 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 0vMGV+gA S7ulsvVIF8LCLdlCiPP3L16B1P1MDGF3xNa0RfDSpWLYKYO0Ny1+VDevp7cQrIK5l8cQ5cprN0DcP0mT0nn4FgJqH1TFf1cEtQTYLc35n+3NldeqiAJeybrazRWpmBxTNf188OSL1KhMs/ThzelhkL5WUSKd4SbtKAgSAAJk1NBaB7m1P8sDZDIj5O58rZDt/7TkH8lEDtnA99ogQ8+eDbGhUM/tJahqbt29Q/lBWnQ0ZFlhXK0G5xBfD8cdG0wYLnb3+ROcsl5inOINUKLMoWyjutQFngoLhOYsiZPF+zUrvpV4rJ7agqlzVq1Bd+ObOrWOAU1Ab2kucm4IUjQmxfhHz+1C1lUIdy9a4gfvuXK1AXOk= 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 06/10/25 11:21 pm, Roman Gushchin wrote: > Commit 4687fdbb805a ("mm/filemap: Support VM_HUGEPAGE for file mappings") > introduced a special handling for VM_HUGEPAGE mappings: even if the > readahead is disabled, 1 or 2 HPAGE_PMD_ORDER pages are > allocated. > > This change causes a significant regression for containers with a > tight memory.max limit, if VM_HUGEPAGE is widely used. Prior to this > commit, mmap_miss logic would eventually lead to the readahead > disablement, effectively reducing the memory pressure in the > cgroup. With this change the kernel is trying to allocate 1-2 huge > pages for each fault, no matter if these pages are used or not > before being evicted, increasing the memory pressure multi-fold. > > To fix the regression, let's make the new VM_HUGEPAGE conditional > to the mmap_miss check, but keep independent from the ra->ra_pages. > This way the main intention of commit 4687fdbb805a ("mm/filemap: > Support VM_HUGEPAGE for file mappings") stays intact, but the > regression is resolved. > > The logic behind this changes is simple: even if a user explicitly > requests using huge pages to back the file mapping (using VM_HUGEPAGE > flag), under a very strong memory pressure it's better to fall back > to ordinary pages. > > Signed-off-by: Roman Gushchin > Cc: Matthew Wilcox (Oracle) > Cc: Jan Kara > Cc: Dev Jain > Cc: linux-mm@kvack.org > > -- > > v3: fixed VM_SEQ_READ handling for the THP case (by Jan Kara) > v2: fixed VM_SEQ_READ handling (by Dev Jain) > > LGTM Reviewed-by: Dev Jain