From nobody Tue Apr 7 10:38:50 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id ED844ECAAD2 for ; Mon, 29 Aug 2022 21:28:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230011AbiH2V15 (ORCPT ); Mon, 29 Aug 2022 17:27:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33442 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229600AbiH2V1I (ORCPT ); Mon, 29 Aug 2022 17:27:08 -0400 Received: from mail-pl1-x64a.google.com (mail-pl1-x64a.google.com [IPv6:2607:f8b0:4864:20::64a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 143D8979F0 for ; Mon, 29 Aug 2022 14:26:18 -0700 (PDT) Received: by mail-pl1-x64a.google.com with SMTP id t13-20020a170902e84d00b00174b03be629so3066595plg.16 for ; Mon, 29 Aug 2022 14:26:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc; bh=plnLK4otWaGxR+W8sd3fBxFm06LW87+WFj6YX7JmKJI=; b=O7Fq7HWZ7z8n2j/HcxIFYSMFkVCbPksq++2+VIS66vXRQwbI7dU8JTklRI8MPiby2e edzsUySG6IImo6mrh8ENCQ2+wxA6BfMFPfkVn5AwXOsZupGcnzhGGSKXttVqFe7CqMCi 1h3acQOuI10/ig3PP8xkKsm4NtzNbHGpaQpLwoGjKN2BSoc/HFLvkEbHUIkKXG5J3g9z 9q6Jpb0Ph5QlVq/4hF27NyIuM3/V2/KAkuHoouSJodEv2dWsfVfE58VeJPPY/+QOUQfz r+QwUf2vpfx2TV1s2fbWWB8eIKopRLMSEdWWEDiBiVoTpxt/dnwqSCw7tnlmHUsJj3fT 5A2Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc; bh=plnLK4otWaGxR+W8sd3fBxFm06LW87+WFj6YX7JmKJI=; b=An68qMb3BQkaDFoaTCxxaamXw5oAoZjEZ7URrhoAlVLhpPPeIod/NjRIeZ/XAJELtP SdGjfhkagpI+4ovYHYfoh0wHCiouDbkhANyMYodmk0cGBhsLdPWXs/5aPwHYd3afAgaY 0L8TekAY3mwVPvfb8uyAIpm9+E5T2Cn8658i28tbHqjQyPyzGNqlkYvay1fVTBV/gxWT TEUEycUn29XF8BshCGVVxbGfqJmNLiDxs/Zl6VLMe2hYtMQlco6srBdoi8B5umRZfSks /FIKwo7LY2PSn61X5Smh3RNo7PsvmoKSDpL+idWeY7NCj6PgOiPkZTG7/MbEtUmqW0lw UwmQ== X-Gm-Message-State: ACgBeo2EsFHSUIqvf1DUgRM5kcCBycJEV/nx+1wFHuzeZIFIEHnQjKAU O99mch1GH+nLfRxtKzykcdvKqt1VyDM= X-Google-Smtp-Source: AA6agR6koDuvaTUSC7OU/WlAja75jS99jSayBh5syt6ErVM0PHA+biyxUvs5Ar838YXdhWnvkXm6gonES4M= X-Received: from surenb-spec.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:3e30]) (user=surenb job=sendgmr) by 2002:a05:6a00:14c7:b0:52e:efb7:bd05 with SMTP id w7-20020a056a0014c700b0052eefb7bd05mr17908102pfu.24.1661808374985; Mon, 29 Aug 2022 14:26:14 -0700 (PDT) Date: Mon, 29 Aug 2022 21:25:25 +0000 In-Reply-To: <20220829212531.3184856-1-surenb@google.com> Mime-Version: 1.0 References: <20220829212531.3184856-1-surenb@google.com> X-Mailer: git-send-email 2.37.2.672.g94769d06f0-goog Message-ID: <20220829212531.3184856-23-surenb@google.com> Subject: [RFC PATCH 22/28] x86/mm: try VMA lock-based page fault handling first From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@techsingularity.net, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, peterz@infradead.org, ldufour@linux.ibm.com, laurent.dufour@fr.ibm.com, paulmck@kernel.org, riel@surriel.com, luto@kernel.org, songliubraving@fb.com, peterx@redhat.com, david@redhat.com, dhowells@redhat.com, hughd@google.com, bigeasy@linutronix.de, kent.overstreet@linux.dev, rientjes@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, surenb@google.com, kernel-team@android.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Attempt VMA lock-based page fault handling first, and fall back to the existing mmap_lock-based handling if that fails. Signed-off-by: Suren Baghdasaryan --- arch/x86/mm/fault.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index fa71a5d12e87..35e74e3dc2c1 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -19,6 +19,7 @@ #include /* faulthandler_disabled() */ #include /* efi_crash_gracefully_on_page_fault()*/ #include +#include /* find_and_lock_vma() */ =20 #include /* boot_cpu_has, ... */ #include /* dotraplinkage, ... */ @@ -1323,6 +1324,38 @@ void do_user_addr_fault(struct pt_regs *regs, } #endif =20 +#ifdef CONFIG_PER_VMA_LOCK + if (!(flags & FAULT_FLAG_USER) || atomic_read(&mm->mm_users) =3D=3D 1) + goto lock_mmap; + + vma =3D find_and_lock_anon_vma(mm, address); + if (!vma) + goto lock_mmap; + + if (unlikely(access_error(error_code, vma))) { + vma_read_unlock(vma); + goto lock_mmap; + } + fault =3D handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs= ); + vma_read_unlock(vma); + + if (!(fault & VM_FAULT_RETRY)) { + count_vm_vma_lock_event(VMA_LOCK_SUCCESS); + goto done; + } + count_vm_vma_lock_event(VMA_LOCK_RETRY); + + /* Quick path to respond to signals */ + if (fault_signal_pending(fault, regs)) { + if (!user_mode(regs)) + kernelmode_fixup_or_oops(regs, error_code, address, + SIGBUS, BUS_ADRERR, + ARCH_DEFAULT_PKEY); + return; + } +lock_mmap: +#endif /* CONFIG_PER_VMA_LOCK */ + /* * Kernel-mode access to the user address space should only occur * on well-defined single instructions listed in the exception @@ -1423,6 +1456,9 @@ void do_user_addr_fault(struct pt_regs *regs, } =20 mmap_read_unlock(mm); +#ifdef CONFIG_PER_VMA_LOCK +done: +#endif if (likely(!(fault & VM_FAULT_ERROR))) return; =20 --=20 2.37.2.672.g94769d06f0-goog