From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Hildenbrand Subject: [PATCH mm-unstable v1 07/20] mm: don't call vm_ops->huge_fault() in wp_huge_pmd()/wp_huge_pud() for private mappings Date: Wed, 16 Nov 2022 11:26:46 +0100 Message-ID: <20221116102659.70287-8-david@redhat.com> References: <20221116102659.70287-1-david@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=9kMU9uTTmnSTu2o7Br7ipFnqvoMBxuiEpQUXAPRL6H8=; b=u9f+ZDFy5nsATy aR8exTVjF0tTx8MNPbySObmcwrLRsTFZv9ybzcyGuSV2MXy5bM1ErVzCbzsZd4rQXs3z6v+XDrkem NmFgpgqr0vwhyqWcgTuXo6TjItqX/VStMMZdubz5IOZ3Qd/jnVeIo7wu3s8ckw3Jd1pfgoAtQzE15 RLmlVrpoqWs+hFE7P8rW2J3+PoWnGiJq+cbrPH8Ox108ZZDRo2iruCw3BJbrXYLDXiuqG7c19C9Oj KZhSN+QJki/dy+fEkCQYUjnhEya4DiBXuggI0PZqed0lA8BjxQesLTjb3avmcfXvKmDWOfMiT41rI UA1TescOFXw55oFVqeqw==; DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1668594501; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=G7hQ0RjvfvFzJ7xHsADTRuI/sN47/U3pNJiDmnh86Zg=; b=DNtyZUGaBEoMHb4dk2woqqxcvh3uRZ5IxEIlqKOrO+29uwYW0/xZaduQ++/eOzZsw5fmzI kdJGAFGuXTBCdzm64Tb2jwx26vV05u/G2XDZxL/ezWrKFRfDchC9DtormYTQZ8VENNBJB2 ZgY5p7IHIJY+xPlR0R7fL0N9/2PtxZI= In-Reply-To: <20221116102659.70287-1-david@redhat.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-um" Errors-To: linux-um-bounces+glud-user-mode-linux-devel=m.gmane-mx.org@lists.infradead.org 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 <> 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