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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: c8eicxx7k8g6kcq371cd6adaoko1xkok X-Rspam-User: X-Rspamd-Queue-Id: 2D58E40003 X-Rspamd-Server: rspam04 X-HE-Tag: 1759726095-329206 X-HE-Meta: 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 z8GozlMH HxE/0lb/SY7isLL/h5Mui221k4R598iumJzQSaO2oeDn+bINA3HaN7ZDyII6jGBPJkJvFhtKrhB06zvPK9DPBzSCEZKA5cHlSvMCEDwh4C0PiOOelMu3bIjOeyah3PezCTQrERZxtSva9QyE3/vmm8+qGPxVs0JdWgSL62BzDzzICIlU/aBHyDKDk2FuCH2zrkuF0D64APA5X7jIJEAfSlTW4EPZcza60GrO2GSH7zSWOLcRCRnKo5OrIAQC4SuXELT6A66lYdujWlbT4BgRU6D1rsdeuhrLxcpmzEBfwUfHrtZzoEXGpJ4EbnFUQ3SXexWz+UgZnk0dgToARs9iaKgIFfoXhCwjDsLBqZquNcsluT24= 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 7:24 am, 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 > Reviewed-by: Jan Kara > Cc: Matthew Wilcox (Oracle) > Cc: Dev Jain > Cc: linux-mm@kvack.org > > -- > > v2: fixed VM_SEQ_READ handling (by Dev Jain) > As you said in a previous mail, we definitely need some other way of measuring memory pressure here. Since your workload is doing madvise(MADV_HUGEPAGE) (which means it expects to take advantage of the hugepage by accessing it frequently) and still getting lots of cache misses, I guess it must be due to swapping out due to tight memory.max. Anyways, the change looks correct to me. Reviewed-by: Dev Jain