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[2620:137:e000::1:20]) by mx.google.com with ESMTP id q2-20020a637502000000b0053f33ec5635si1813757pgc.865.2023.06.08.18.00.06; Thu, 08 Jun 2023 18:00:19 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20221208 header.b=aoHc7JPC; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229661AbjFIAwh (ORCPT + 99 others); Thu, 8 Jun 2023 20:52:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51726 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234892AbjFIAwO (ORCPT ); Thu, 8 Jun 2023 20:52:14 -0400 Received: from mail-pg1-x54a.google.com (mail-pg1-x54a.google.com [IPv6:2607:f8b0:4864:20::54a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C68AC2685 for ; Thu, 8 Jun 2023 17:52:12 -0700 (PDT) Received: by mail-pg1-x54a.google.com with SMTP id 41be03b00d2f7-53b9eb7bda0so220334a12.0 for ; Thu, 08 Jun 2023 17:52:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1686271932; x=1688863932; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=uuo3Il/2NbgOWAM0rjqTihVZSZhUnoZMQ/ESG1PbGOc=; b=aoHc7JPCZ32CAYt9q46WDYGEOxxS+8Zg8n+MkQ8tBFVy2AxaNM8+3Gds918auhPTHa q1i93JJIOBjYqWdat77Bw43ovYfILELgsQ3A15M4ncn74YtVwsuP81alu9yqHz/6QEf4 0ZCIwnE+WqrId9F8Np2B9UzySwNVPcW9qaPUxrGBEsK8nkCGUUE7v/JS22HdzPoOb4MB Chi4Dc24/vK44G+H3O7mb/dNtV3gVAS4dKZye3QS8d/JCKeQ8FR8f6Rt4chkxNrZVvil NBHO4/LslE98QkZt8lZcAJ+QXDZaDtGSI1vY2Loous6hPUzUbnAktXCDF6R5gPFfIwoD hcMw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1686271932; x=1688863932; 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=uuo3Il/2NbgOWAM0rjqTihVZSZhUnoZMQ/ESG1PbGOc=; b=W696qUNB0XBmguvWzibGh1+7V+4mPcC0oBIxXjHuCYY6D1P/iaEob+oQwyEqnNJK1g 0Zqr5AJlb2yOWOHKIUejie2Woq4h52fgBSoMPTySj1ZCRDTVL/zaDG/eyY/BmHXEM0gu kqSSXR9ohk6muSNs9oppWIVU14CflfpdV9nyuO+iGx+e0ENHt1eYWjJ+Usv7UklU0CNI U8aN11MIDeeWk1KXYOAu/cn10B2jkU2e3REG/3gRPkfkYVVG5y5sKL6l9xxFErZLriAy lvQwAiM5U68S8yivgpSGetwBJAhIpIt2H9CA8wn9/SCGb6RXJEhm0grSF7f6c+D+J81s J1/g== X-Gm-Message-State: AC+VfDw7AMq/UqIMU/CQtkye9W+oLEpgZJDAeVs4iiL5kKRM8aKXd+XZ ZGcMoJepZiCK1G7VutpyXz/VzcaZXSM= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:201:c03e:d3b7:767a:9467]) (user=surenb job=sendgmr) by 2002:a63:d44:0:b0:503:77c9:45aa with SMTP id 4-20020a630d44000000b0050377c945aamr225410pgn.9.1686271932107; Thu, 08 Jun 2023 17:52:12 -0700 (PDT) Date: Thu, 8 Jun 2023 17:51:56 -0700 In-Reply-To: <20230609005158.2421285-1-surenb@google.com> Mime-Version: 1.0 References: <20230609005158.2421285-1-surenb@google.com> X-Mailer: git-send-email 2.41.0.162.gfafddb0af9-goog Message-ID: <20230609005158.2421285-5-surenb@google.com> Subject: [PATCH v2 4/6] mm: drop VMA lock before waiting for migration 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 X-Spam-Status: No, score=-9.6 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE,USER_IN_DEF_DKIM_WL autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1768184788353554269?= X-GMAIL-MSGID: =?utf-8?q?1768184788353554269?= migration_entry_wait does not need VMA lock, therefore it can be dropped before waiting. Introduce VM_FAULT_VMA_UNLOCKED to indicate that VMA lock was dropped while in handle_mm_fault(). Note that once VMA lock is dropped, the VMA reference can't be used as there are no guarantees it was not freed. Signed-off-by: Suren Baghdasaryan --- arch/arm64/mm/fault.c | 3 ++- arch/powerpc/mm/fault.c | 3 ++- arch/s390/mm/fault.c | 3 ++- arch/x86/mm/fault.c | 3 ++- include/linux/mm_types.h | 6 +++++- mm/memory.c | 12 ++++++++++-- 6 files changed, 23 insertions(+), 7 deletions(-) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 6045a5117ac1..8f59badbffb5 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -601,7 +601,8 @@ 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_VMA_UNLOCKED)) + 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 531177a4ee08..b27730f07141 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -494,7 +494,8 @@ 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_VMA_UNLOCKED)) + 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 b65144c392b0..cc923dbb0821 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_VMA_UNLOCKED)) + 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 e4399983c50c..ef62ab2fd211 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1347,7 +1347,8 @@ 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_VMA_UNLOCKED)) + vma_end_read(vma); if (!(fault & VM_FAULT_RETRY)) { count_vm_vma_lock_event(VMA_LOCK_SUCCESS); diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 79765e3dd8f3..bd6b95c82f7a 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -1030,6 +1030,8 @@ typedef __bitwise unsigned int vm_fault_t; * fsync() to complete (for synchronous page faults * in DAX) * @VM_FAULT_COMPLETED: ->fault completed, meanwhile mmap lock released + * @VM_FAULT_VMA_UNLOCKED: VMA lock was released, vmf->vma should no longer + * be accessed * @VM_FAULT_HINDEX_MASK: mask HINDEX value * */ @@ -1047,6 +1049,7 @@ enum vm_fault_reason { VM_FAULT_DONE_COW = (__force vm_fault_t)0x001000, VM_FAULT_NEEDDSYNC = (__force vm_fault_t)0x002000, VM_FAULT_COMPLETED = (__force vm_fault_t)0x004000, + VM_FAULT_VMA_UNLOCKED = (__force vm_fault_t)0x008000, VM_FAULT_HINDEX_MASK = (__force vm_fault_t)0x0f0000, }; @@ -1071,7 +1074,8 @@ enum vm_fault_reason { { VM_FAULT_FALLBACK, "FALLBACK" }, \ { VM_FAULT_DONE_COW, "DONE_COW" }, \ { VM_FAULT_NEEDDSYNC, "NEEDDSYNC" }, \ - { VM_FAULT_COMPLETED, "COMPLETED" } + { VM_FAULT_COMPLETED, "COMPLETED" }, \ + { VM_FAULT_VMA_UNLOCKED, "VMA_UNLOCKED" } struct vm_special_mapping { const char *name; /* The name, e.g. "[vdso]". */ diff --git a/mm/memory.c b/mm/memory.c index 41f45819a923..c234f8085f1e 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3714,8 +3714,16 @@ vm_fault_t do_swap_page(struct vm_fault *vmf) entry = pte_to_swp_entry(vmf->orig_pte); if (unlikely(non_swap_entry(entry))) { if (is_migration_entry(entry)) { - migration_entry_wait(vma->vm_mm, vmf->pmd, - vmf->address); + /* Save mm in case VMA lock is dropped */ + struct mm_struct *mm = vma->vm_mm; + + if (vmf->flags & FAULT_FLAG_VMA_LOCK) { + /* No need to hold VMA lock for migration */ + vma_end_read(vma); + /* WARNING: VMA can't be used after this */ + ret |= VM_FAULT_VMA_UNLOCKED; + } + migration_entry_wait(mm, vmf->pmd, vmf->address); } else if (is_device_exclusive_entry(entry)) { vmf->page = pfn_swap_entry_to_page(entry); ret = remove_device_exclusive_entry(vmf);