From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Date: Wed, 16 Nov 2022 10:26:46 +0000 Subject: [PATCH mm-unstable v1 07/20] mm: don't call vm_ops->huge_fault() in wp_huge_pmd()/wp_huge_pud() for Message-Id: <20221116102659.70287-8-david@redhat.com> List-Id: References: <20221116102659.70287-1-david@redhat.com> In-Reply-To: <20221116102659.70287-1-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-kernel@vger.kernel.org Cc: x86@kernel.org, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-ia64@vger.kernel.org, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, etnaviv@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-samsung-soc@vger.kernel.org, linux-rdma@vger.kernel.org, linux-media@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-perf-users@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kselftest@vger.kernel.org, Linus Torvalds , Andrew Morton , Jason Gunthorpe , John Hubbard , Peter Xu , Greg Kroah-Hartman , Andrea Arcangeli , Hugh Dickins , Nadav Amit , Vlastimil Babka , Matthew Wilcox , Mike Kravetz , Muchun Song , Shuah Khan , Lucas Stach , David Airlie , Oded Gabbay , Arnd Bergmann , Christoph Hellwig , Alex Williamson , David Hildenbrand If we already have a PMD/PUD mapped write-protected in a private mapping and we want to break COW either due to FAULT_FLAG_WRITE or FAULT_FLAG_UNSHARE, there is no need to inform the file system just like on the PTE path. Let's just split (->zap) + fallback in that case. This is a preparation for more generic FAULT_FLAG_UNSHARE support in COW mappings. Signed-off-by: David Hildenbrand --- mm/memory.c | 24 +++++++++++++++--------- 1 file changed, 15 insertions(+), 9 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index c35e6cd32b6a..d47ad33c6487 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4802,6 +4802,7 @@ static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf) static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf) { const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; + vm_fault_t ret; if (vma_is_anonymous(vmf->vma)) { if (likely(!unshare) && @@ -4809,11 +4810,13 @@ static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf) return handle_userfault(vmf, VM_UFFD_WP); return do_huge_pmd_wp_page(vmf); } - if (vmf->vma->vm_ops->huge_fault) { - vm_fault_t ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD); - if (!(ret & VM_FAULT_FALLBACK)) - return ret; + if (vmf->vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) { + if (vmf->vma->vm_ops->huge_fault) { + ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD); + if (!(ret & VM_FAULT_FALLBACK)) + return ret; + } } /* COW or write-notify handled on pte level: split pmd. */ @@ -4839,14 +4842,17 @@ static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud) { #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \ defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) + vm_fault_t ret; + /* No support for anonymous transparent PUD pages yet */ if (vma_is_anonymous(vmf->vma)) goto split; - if (vmf->vma->vm_ops->huge_fault) { - vm_fault_t ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD); - - if (!(ret & VM_FAULT_FALLBACK)) - return ret; + if (vmf->vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) { + if (vmf->vma->vm_ops->huge_fault) { + ret = vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD); + if (!(ret & VM_FAULT_FALLBACK)) + return ret; + } } split: /* COW or write-notify not handled on PUD level: split pud.*/ -- 2.38.1