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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1rNXwE-00BQos-8L; Wed, 10 Jan 2024 12:44:06 +0000 Date: Wed, 10 Jan 2024 12:44:06 +0000 From: Matthew Wilcox To: Chen Haixiang Cc: linux-mm@kvack.org, akpm@linux-foundation.org, hughd@google.com, louhongxiang@huawei.com, wangbin224@huawei.com, liuyuntao10@huawei.com Subject: Re: [PATCH] support tmpfs hugepage PMD is not split when COW Message-ID: References: <20240110092028.1777-1-chenhaixiang3@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240110092028.1777-1-chenhaixiang3@huawei.com> X-Rspamd-Queue-Id: 7BF45180018 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: 33xx7zo5fo4cep733thmh1oqqzftw7bh X-HE-Tag: 1704890651-282096 X-HE-Meta: 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 ywsa379F vzaXhq8z158hMvGsGi5j6zCUr8uIgTNudgROYMQHhKMe5ta2vuuSxcEz87K6voVv4YlQNM1aEH4LRdOMifp4Z2iRyujDraof3mhn6HMLgFaEa1CM0kWT9g3XKS6xWUgDdX3s6x0ilQnjNbvE= 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 Wed, Jan 10, 2024 at 05:20:28PM +0800, Chen Haixiang wrote: > +++ b/include/linux/mm.h > @@ -573,6 +573,7 @@ struct vm_operations_struct { > unsigned long end, unsigned long newflags); > vm_fault_t (*fault)(struct vm_fault *vmf); > vm_fault_t (*huge_fault)(struct vm_fault *vmf, unsigned int order); > + vm_fault_t (*shmem_huge_fault)(struct vm_fault *vmf, pmd_t orig_pmd); No new operation for this. > +++ b/mm/memory.c > @@ -4942,6 +4942,13 @@ static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf) > } > } > > + if (vmf->vma->vm_ops->shmem_huge_fault) { > + vm_fault_t ret = vmf->vma->vm_ops->shmem_huge_fault(vmf, vmf->orig_pmd); > + > + if (!(ret & VM_FAULT_FALLBACK)) > + return ret; > + } Why would you do this when ->huge_fault is called in the stanza above?