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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mfpsO-000JRN-Nm; Wed, 27 Oct 2021 20:50:30 +0000 Date: Wed, 27 Oct 2021 21:50:24 +0100 From: Matthew Wilcox To: Yang Shi Cc: hughd@google.com, sunhao.th@gmail.com, kirill.shutemov@linux.intel.com, songliubraving@fb.com, andrea.righi@canonical.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] mm: khugepaged: skip huge page collapse for special files Message-ID: References: <20211027195221.3825-1-shy828301@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211027195221.3825-1-shy828301@gmail.com> X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 84B21F000204 X-Stat-Signature: bmto3gtx61os977jkgrtjre774ztjpaw Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=pRkShx82; dmarc=none; spf=none (imf11.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-HE-Tag: 1635367900-685611 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: On Wed, Oct 27, 2021 at 12:52:21PM -0700, Yang Shi wrote: > +++ b/mm/khugepaged.c > @@ -445,22 +445,25 @@ static bool hugepage_vma_check(struct vm_area_struct *vma, > if (!transhuge_vma_enabled(vma, vm_flags)) > return false; > > - /* Enabled via shmem mount options or sysfs settings. */ > - if (shmem_file(vma->vm_file) && shmem_huge_enabled(vma)) { > + if (vma->vm_file) > return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff, > HPAGE_PMD_NR); > - } > + > + /* Enabled via shmem mount options or sysfs settings. */ > + if (shmem_file(vma->vm_file)) > + return shmem_huge_enabled(vma); This doesn't make sense to me. if vma->vm_file, we already returned, so this is dead code. > /* THP settings require madvise. */ > if (!(vm_flags & VM_HUGEPAGE) && !khugepaged_always()) > return false; > > - /* Read-only file mappings need to be aligned for THP to work. */ > + /* Only regular file is valid */ > if (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && vma->vm_file && > - !inode_is_open_for_write(vma->vm_file->f_inode) && > (vm_flags & VM_EXEC)) { > - return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff, > - HPAGE_PMD_NR); > + struct inode *inode = vma->vm_file->f_inode; > + > + return !inode_is_open_for_write(inode) && > + S_ISREG(inode->i_mode); > } > > if (!vma->anon_vma || vma->vm_ops) > -- > 2.26.2 >