From patchwork Fri Jun 30 02:04:32 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Suren Baghdasaryan X-Patchwork-Id: 13297506 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 7530BEB64DD for ; Fri, 30 Jun 2023 02:05:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232029AbjF3CE7 (ORCPT ); Thu, 29 Jun 2023 22:04:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48660 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231927AbjF3CEt (ORCPT ); Thu, 29 Jun 2023 22:04:49 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8A6DC19A9 for ; Thu, 29 Jun 2023 19:04:47 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id 3f1490d57ef6-c3d29d2fdffso978749276.2 for ; Thu, 29 Jun 2023 19:04:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1688090687; x=1690682687; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=V7p+xkeFpHpY+8imX6dpZwoTYVp943eibQ5qK+rLf3c=; b=DUV7BVM9nFkRrG4OmL2z1rbzNQPYA08eD/W6CM9ZTP8ycZScg2wT7L7+zDm47i3EEp YYXhyTKoKtmqRcvzOyTyV44bllZXd+7i1AMkEKCnp9VhDpEzAvKcS+2YEZK4NAZsYcoe y/bdw210HSJrZUvj1zbrUaU+YWomeS88ogbqihRlgl+T+b4TNg18Gr+BlED4NnaQkkkw f1IhR/XhDFUZ7ovgt4RYv6+3pQDpmsTR7as7++jPBwf7pFCGJ+iXgGbx70KDjUWJPZkG Jf9I49Iy4KlltuDt6TFCOy2p6d0dzZ9NTdp0L/acX6A4axhyfobo5rKVJIXrfSI6c/Al EGHg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1688090687; x=1690682687; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=V7p+xkeFpHpY+8imX6dpZwoTYVp943eibQ5qK+rLf3c=; b=TdmkwIo/Xlw0lIiyv6hEI9Z5pf/l/3O6dOkS0flKR+zfDfJVwYGia3d1Xf/I6MaEkp W12x6GBAqbAEULc/6oDSz3W2yE/wxSRkYGGlxrx0NDyTiQ/Hey4Mtiqx8aOy2VUywDYB W/LkJnq3dB1qmBSxmKlvqb2D5ch0jw1atrCunP2ZVi1vpVC7rxtfmeCQ5JlFJWpPeEwh rH2vjG5mtEbyn3mnP901OJub3r6MymSbO1wAG0LkrjcfH11+1EOuxnN7lWsRcH01C0Qm IFhth/PkVSbN90YI3ZbF4ZEEpyYI5RIX9M62h0PXlNOfqR5Woeuq2TwMEpg/39XtzjzS pqPQ== X-Gm-Message-State: ABy/qLY4mlEYGOxlxZPhXdHkbh4rl6FgzHPSw6fzpOFJxeG9PAGget+D Rz3acoRnk9SarciB1HIc0CtOfnTO++4= X-Google-Smtp-Source: APBJJlEey6/2V3MIX/R8fPAMY5b+xzPIZFVw7itp9GblxpDJfWRGEmOCyuEH2lOm02vp1cSgPAo6FSaIDcg= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:201:1f11:a3d0:19a9:16e5]) (user=surenb job=sendgmr) by 2002:a5b:a01:0:b0:c1d:d3e6:d52e with SMTP id k1-20020a5b0a01000000b00c1dd3e6d52emr10821ybq.0.1688090686807; Thu, 29 Jun 2023 19:04:46 -0700 (PDT) Date: Thu, 29 Jun 2023 19:04:32 -0700 In-Reply-To: <20230630020436.1066016-1-surenb@google.com> Mime-Version: 1.0 References: <20230630020436.1066016-1-surenb@google.com> X-Mailer: git-send-email 2.41.0.255.g8b1d071c50-goog Message-ID: <20230630020436.1066016-4-surenb@google.com> Subject: [PATCH v6 3/6] mm: drop per-VMA lock when returning VM_FAULT_RETRY or VM_FAULT_COMPLETED From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: willy@infradead.org, hannes@cmpxchg.org, mhocko@suse.com, josef@toxicpanda.com, jack@suse.cz, ldufour@linux.ibm.com, laurent.dufour@fr.ibm.com, michel@lespinasse.org, liam.howlett@oracle.com, jglisse@google.com, vbabka@suse.cz, minchan@google.com, dave@stgolabs.net, punit.agrawal@bytedance.com, lstoakes@gmail.com, hdanton@sina.com, apopple@nvidia.com, peterx@redhat.com, ying.huang@intel.com, david@redhat.com, yuzhao@google.com, dhowells@redhat.com, hughd@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, pasha.tatashin@soleen.com, surenb@google.com, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org handle_mm_fault returning VM_FAULT_RETRY or VM_FAULT_COMPLETED means mmap_lock has been released. However with per-VMA locks behavior is different and the caller should still release it. To make the rules consistent for the caller, drop the per-VMA lock when returning VM_FAULT_RETRY or VM_FAULT_COMPLETED. Currently the only path returning VM_FAULT_RETRY under per-VMA locks is do_swap_page and no path returns VM_FAULT_COMPLETED for now. Signed-off-by: Suren Baghdasaryan Acked-by: Peter Xu --- arch/arm64/mm/fault.c | 3 ++- arch/powerpc/mm/fault.c | 3 ++- arch/s390/mm/fault.c | 3 ++- arch/x86/mm/fault.c | 3 ++- mm/memory.c | 12 ++++++++++++ 5 files changed, 20 insertions(+), 4 deletions(-) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 935f0a8911f9..9d78ff78b0e3 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -602,7 +602,8 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr, goto lock_mmap; } fault = handle_mm_fault(vma, addr, mm_flags | FAULT_FLAG_VMA_LOCK, regs); - vma_end_read(vma); + if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED))) + vma_end_read(vma); if (!(fault & VM_FAULT_RETRY)) { count_vm_vma_lock_event(VMA_LOCK_SUCCESS); diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 5bfdf6ecfa96..82954d0e6906 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -489,7 +489,8 @@ static int ___do_page_fault(struct pt_regs *regs, unsigned long address, } fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs); - vma_end_read(vma); + if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED))) + vma_end_read(vma); if (!(fault & VM_FAULT_RETRY)) { count_vm_vma_lock_event(VMA_LOCK_SUCCESS); diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c index dbe8394234e2..40a71063949b 100644 --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -418,7 +418,8 @@ static inline vm_fault_t do_exception(struct pt_regs *regs, int access) goto lock_mmap; } fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs); - vma_end_read(vma); + if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED))) + vma_end_read(vma); if (!(fault & VM_FAULT_RETRY)) { count_vm_vma_lock_event(VMA_LOCK_SUCCESS); goto out; diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index e8711b2cafaf..56b4f9faf8c4 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1341,7 +1341,8 @@ void do_user_addr_fault(struct pt_regs *regs, goto lock_mmap; } fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs); - vma_end_read(vma); + if (!(fault & (VM_FAULT_RETRY | VM_FAULT_COMPLETED))) + vma_end_read(vma); if (!(fault & VM_FAULT_RETRY)) { count_vm_vma_lock_event(VMA_LOCK_SUCCESS); diff --git a/mm/memory.c b/mm/memory.c index 0ae594703021..5f26c56ce979 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3730,6 +3730,7 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) if (vmf->flags & FAULT_FLAG_VMA_LOCK) { ret = VM_FAULT_RETRY; + vma_end_read(vma); goto out; } @@ -5182,6 +5183,17 @@ static vm_fault_t sanitize_fault_flags(struct vm_area_struct *vma, !is_cow_mapping(vma->vm_flags))) return VM_FAULT_SIGSEGV; } +#ifdef CONFIG_PER_VMA_LOCK + /* + * Per-VMA locks can't be used with FAULT_FLAG_RETRY_NOWAIT because of + * the assumption that lock is dropped on VM_FAULT_RETRY. + */ + if (WARN_ON_ONCE((*flags & + (FAULT_FLAG_VMA_LOCK | FAULT_FLAG_RETRY_NOWAIT)) == + (FAULT_FLAG_VMA_LOCK | FAULT_FLAG_RETRY_NOWAIT))) + return VM_FAULT_SIGSEGV; +#endif + return 0; }