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[2620:137:e000::1:20]) by mx.google.com with ESMTP id t196-20020a6378cd000000b004791644f520si11274456pgc.437.2023.02.06.00.44.25; Mon, 06 Feb 2023 00:44:39 -0800 (PST) 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=@redhat.com header.s=mimecast20190719 header.b=Wza+ghHr; 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=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229727AbjBFIl5 (ORCPT + 99 others); Mon, 6 Feb 2023 03:41:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56204 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229993AbjBFIln (ORCPT ); Mon, 6 Feb 2023 03:41:43 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 550F217145 for ; Mon, 6 Feb 2023 00:40:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675672853; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=qDthkt1yrsdVPAFblgfFdo4HNws2a1WpfRKMjlx3T68=; b=Wza+ghHrUUAPL77B6S7ekG/Bs4SQET6zBoV9ksNqbqhVYZeQbTqlYddLI8b6kxD67tl3qx juYDxW2SIeavfYtunI2xPtTp040wTy+4H6FPKanNr+p2r+/hHNTkgFQJo0lnXPt2K+rjkh 9/nCVVqG/wnJesAXWn9KEdlwF5Qm5BI= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-620-GfzowxhZMZyVQncuaXs6Yw-1; Mon, 06 Feb 2023 03:40:42 -0500 X-MC-Unique: GfzowxhZMZyVQncuaXs6Yw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 2F7C5858F0E; Mon, 6 Feb 2023 08:40:42 +0000 (UTC) Received: from MiWiFi-R3L-srv.redhat.com (ovpn-12-71.pek2.redhat.com [10.72.12.71]) by smtp.corp.redhat.com (Postfix) with ESMTP id 14BF52166B2A; Mon, 6 Feb 2023 08:40:37 +0000 (UTC) From: Baoquan He To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, akpm@linux-foundation.org, stephen.s.brennan@oracle.com, urezki@gmail.com, lstoakes@gmail.com, error27@gmail.com, Baoquan He Subject: [PATCH v5 3/7] mm/vmalloc.c: allow vread() to read out vm_map_ram areas Date: Mon, 6 Feb 2023 16:40:16 +0800 Message-Id: <20230206084020.174506-4-bhe@redhat.com> In-Reply-To: <20230206084020.174506-1-bhe@redhat.com> References: <20230206084020.174506-1-bhe@redhat.com> MIME-Version: 1.0 Content-type: text/plain X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2,SPF_HELO_NONE,SPF_NONE autolearn=ham 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?1757070569359274954?= X-GMAIL-MSGID: =?utf-8?q?1757070574798212417?= Currently, vread can read out vmalloc areas which is associated with a vm_struct. While this doesn't work for areas created by vm_map_ram() interface because it doesn't have an associated vm_struct. Then in vread(), these areas are all skipped. Here, add a new function vmap_ram_vread() to read out vm_map_ram areas. The area created with vmap_ram_vread() interface directly can be handled like the other normal vmap areas with aligned_vread(). While areas which will be further subdivided and managed with vmap_block need carefully read out page-aligned small regions and zero fill holes. Reported-by: Stephen Brennan Signed-off-by: Baoquan He Reviewed-by: Lorenzo Stoakes Tested-by: Stephen Brennan --- mm/vmalloc.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 81 insertions(+), 7 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index ab4825050b5c..4bb78ebd70f6 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -3544,6 +3544,68 @@ static int aligned_vread(char *buf, char *addr, unsigned long count) return copied; } +static void vmap_ram_vread(char *buf, char *addr, int count, unsigned long flags) +{ + char *start; + struct vmap_block *vb; + unsigned long offset; + unsigned int rs, re, n; + + /* + * If it's area created by vm_map_ram() interface directly, but + * not further subdividing and delegating management to vmap_block, + * handle it here. + */ + if (!(flags & VMAP_BLOCK)) { + aligned_vread(buf, addr, count); + return; + } + + /* + * Area is split into regions and tracked with vmap_block, read out + * each region and zero fill the hole between regions. + */ + vb = xa_load(&vmap_blocks, addr_to_vb_idx((unsigned long)addr)); + if (!vb) + goto finished; + + spin_lock(&vb->lock); + if (bitmap_empty(vb->used_map, VMAP_BBMAP_BITS)) { + spin_unlock(&vb->lock); + goto finished; + } + for_each_set_bitrange(rs, re, vb->used_map, VMAP_BBMAP_BITS) { + if (!count) + break; + start = vmap_block_vaddr(vb->va->va_start, rs); + while (addr < start) { + if (count == 0) + goto unlock; + *buf = '\0'; + buf++; + addr++; + count--; + } + /*it could start reading from the middle of used region*/ + offset = offset_in_page(addr); + n = ((re - rs + 1) << PAGE_SHIFT) - offset; + if (n > count) + n = count; + aligned_vread(buf, start+offset, n); + + buf += n; + addr += n; + count -= n; + } +unlock: + spin_unlock(&vb->lock); + +finished: + /* zero-fill the left dirty or free regions */ + if (count) + memset(buf, 0, count); +} + /** * vread() - read vmalloc area in a safe way. * @buf: buffer for reading data @@ -3574,7 +3636,7 @@ long vread(char *buf, char *addr, unsigned long count) struct vm_struct *vm; char *vaddr, *buf_start = buf; unsigned long buflen = count; - unsigned long n; + unsigned long n, size, flags; addr = kasan_reset_tag(addr); @@ -3595,12 +3657,21 @@ long vread(char *buf, char *addr, unsigned long count) if (!count) break; - if (!va->vm) + vm = va->vm; + flags = va->flags & VMAP_FLAGS_MASK; + /* + * VMAP_BLOCK indicates a sub-type of vm_map_ram area, need + * be set together with VMAP_RAM. + */ + WARN_ON(flags == VMAP_BLOCK); + + if (!vm && !flags) continue; - vm = va->vm; - vaddr = (char *) vm->addr; - if (addr >= vaddr + get_vm_area_size(vm)) + vaddr = (char *) va->va_start; + size = vm ? get_vm_area_size(vm) : va_size(va); + + if (addr >= vaddr + size) continue; while (addr < vaddr) { if (count == 0) @@ -3610,10 +3681,13 @@ long vread(char *buf, char *addr, unsigned long count) addr++; count--; } - n = vaddr + get_vm_area_size(vm) - addr; + n = vaddr + size - addr; if (n > count) n = count; - if (!(vm->flags & VM_IOREMAP)) + + if (flags & VMAP_RAM) + vmap_ram_vread(buf, addr, n, flags); + else if (!(vm->flags & VM_IOREMAP)) aligned_vread(buf, addr, n); else /* IOREMAP area is treated as memory hole */ memset(buf, 0, n);