From nobody Sat Feb 7 05:22:19 2026 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 95235149006 for ; Fri, 26 Apr 2024 14:45:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714142720; cv=none; b=ihHF9Z0bxyy7W1dnxzx2npR/hiAGcMO3n+l767J6EJkxXUNuDTlph0/umqyVEzGZ3wL7dCvZZHeQrSqTEfpSENDHkwYnmtAfh+QEWqkYJzF8a30tN+U4hH2TTJNxK//3FeAe9LHttcJvuwzl52ctQrycwJrFxviWT7vHtVHcsEs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1714142720; c=relaxed/simple; bh=2A0I/wQ02ZQClsJJvC2xC++2okdVlxUH4BTAOBbX1qo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=dLchBwNPU6Bf2DUZiZTGxE8CWEWkJnUbGlXDRem7e23rdTsvZd+a4yGuZ9OaTi3znPeF993dFL1hgpEYnUPvcUA029AG9DviHAAe4gHXtpzhqMSrfpOq/SRXNTmCpK8E6EGO0i7w5uexBVWre9NxpKJesxI+jZyMTY9EqEUg5N8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=avEdWTM/; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="avEdWTM/" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=xiasNW2bjz4XwywyYv4zK4GYnJbH5N9m8U5+b7/FG0g=; b=avEdWTM/yAlNRrylBNlMhcItT8 yT3lf5sbN2RA11wRK57vjoI6+cQ4lOshf22Lj4uL7AZ/b1ZfApFJfPwIoV+o5X89LxrtQKmovdkWp d6GdOd+oLFrtddsrmgjkb3tHhclq/QbDFb2K9UAk9I0CHB+msjtBqcV+NNzBx3RflOlaD9xy8Dxhk es3hCflPEq9bjg0W2B3ZvZt2nuIbUQ94Vbc6N/36fbLOt32SrhktKVGwgIfqJcg4UWo/Y/MU/xiW+ LQeO3PqBRGk0YU47AeSqIQtKcSKBURhocodIXVgGTbeLOQplgj5BFtuB0HLDEw1g+kXORauvDvxQ1 4dMG+cJw==; Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1s0Mp2-00000005Pl6-1hWT; Fri, 26 Apr 2024 14:45:08 +0000 From: "Matthew Wilcox (Oracle)" To: Andrew Morton Cc: "Matthew Wilcox (Oracle)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Suren Baghdasaryan , Peter Xu , Jann Horn Subject: [PATCH 4/4] mm: Optimise vmf_anon_prepare() for VMAs without an anon_vma Date: Fri, 26 Apr 2024 15:45:03 +0100 Message-ID: <20240426144506.1290619-5-willy@infradead.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240426144506.1290619-1-willy@infradead.org> References: <20240426144506.1290619-1-willy@infradead.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" If the mmap_lock can be taken for read, we can call __anon_vma_prepare() while holding it, saving ourselves a trip back through the fault handler. Signed-off-by: Matthew Wilcox (Oracle) Reviewed-by: Jann Horn Reviewed-by: Suren Baghdasaryan Reviewed-by: David Hildenbrand --- mm/memory.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index 7dc112d3a7e4..b5453b86ec4b 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3232,16 +3232,21 @@ static inline vm_fault_t vmf_can_call_fault(const s= truct vm_fault *vmf) vm_fault_t vmf_anon_prepare(struct vm_fault *vmf) { struct vm_area_struct *vma =3D vmf->vma; + vm_fault_t ret =3D 0; =20 if (likely(vma->anon_vma)) return 0; if (vmf->flags & FAULT_FLAG_VMA_LOCK) { - vma_end_read(vma); - return VM_FAULT_RETRY; + if (!mmap_read_trylock(vma->vm_mm)) { + vma_end_read(vma); + return VM_FAULT_RETRY; + } } if (__anon_vma_prepare(vma)) - return VM_FAULT_OOM; - return 0; + ret =3D VM_FAULT_OOM; + if (vmf->flags & FAULT_FLAG_VMA_LOCK) + mmap_read_unlock(vma->vm_mm); + return ret; } =20 /* --=20 2.43.0