From nobody Sat Nov 23 23:34:46 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1728328812411789.6315154913306; Mon, 7 Oct 2024 12:20:12 -0700 (PDT) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sxtEo-0005Br-Dn; Mon, 07 Oct 2024 15:17:46 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sxtEm-0005A5-7l; Mon, 07 Oct 2024 15:17:44 -0400 Received: from isrv.corpit.ru ([86.62.121.231]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sxtEj-0004An-Bw; Mon, 07 Oct 2024 15:17:43 -0400 Received: from tsrv.corpit.ru (tsrv.tls.msk.ru [192.168.177.2]) by isrv.corpit.ru (Postfix) with ESMTP id EE0CE9624B; Mon, 7 Oct 2024 22:16:48 +0300 (MSK) Received: from tls.msk.ru (mjt.wg.tls.msk.ru [192.168.177.130]) by tsrv.corpit.ru (Postfix) with SMTP id C17E814F72B; Mon, 7 Oct 2024 22:16:55 +0300 (MSK) Received: (nullmailer pid 2592743 invoked by uid 1000); Mon, 07 Oct 2024 19:16:54 -0000 From: Michael Tokarev To: qemu-devel@nongnu.org Cc: qemu-stable@nongnu.org, David Hildenbrand , Peter Maydell , Stefan Hajnoczi , Peter Xu , Paolo Bonzini , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Michael Tokarev Subject: [Stable-9.1.1 14/32] softmmu/physmem: fix memory leak in dirty_memory_extend() Date: Mon, 7 Oct 2024 22:16:31 +0300 Message-Id: <20241007191654.2592616-14-mjt@tls.msk.ru> X-Mailer: git-send-email 2.39.5 In-Reply-To: References: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=86.62.121.231; envelope-from=mjt@tls.msk.ru; helo=isrv.corpit.ru X-Spam_score_int: -68 X-Spam_score: -6.9 X-Spam_bar: ------ X-Spam_report: (-6.9 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_HI=-5, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZM-MESSAGEID: 1728328812891116600 From: David Hildenbrand As reported by Peter, we might be leaking memory when removing the highest RAMBlock (in the weird ram_addr_t space), and adding a new one. We will fail to realize that we already allocated bitmaps for more dirty memory blocks, and effectively discard the pointers to them. Fix it by getting rid of last_ram_page() and by remembering the number of dirty memory blocks that have been allocated already. While at it, let's use "unsigned int" for the number of blocks, which should be sufficient until we reach ~32 exabytes. Looks like this leak was introduced as we switched from using a single bitmap_zero_extend() to allocating multiple bitmaps: bitmap_zero_extend() relies on g_renew() which should have taken care of this. Resolves: https://lkml.kernel.org/r/CAFEAcA-k7a+VObGAfCFNygQNfCKL=3DAfX6A4k= Scq=3DVSSK0peqPg@mail.gmail.com Reported-by: Peter Maydell Fixes: 5b82b703b69a ("memory: RCU ram_list.dirty_memory[] for safe RAM hotp= lug") Reviewed-by: Stefan Hajnoczi Reviewed-by: Peter Xu Tested-by: Peter Maydell Cc: qemu-stable@nongnu.org Cc: Stefan Hajnoczi Cc: Paolo Bonzini Cc: Peter Xu Cc: Philippe Mathieu-Daud=C3=A9 Signed-off-by: David Hildenbrand Link: https://lore.kernel.org/r/20240828090743.128647-1-david@redhat.com Signed-off-by: Peter Xu (cherry picked from commit b84f06c2bee727b3870b4eeccbe3a45c5aea14c1) Signed-off-by: Michael Tokarev diff --git a/include/exec/ramlist.h b/include/exec/ramlist.h index 2ad2a81acc..d9cfe530be 100644 --- a/include/exec/ramlist.h +++ b/include/exec/ramlist.h @@ -50,6 +50,7 @@ typedef struct RAMList { /* RCU-enabled, writes protected by the ramlist lock. */ QLIST_HEAD(, RAMBlock) blocks; DirtyMemoryBlocks *dirty_memory[DIRTY_MEMORY_NUM]; + unsigned int num_dirty_blocks; uint32_t version; QLIST_HEAD(, RAMBlockNotifier) ramblock_notifiers; } RAMList; diff --git a/system/physmem.c b/system/physmem.c index 971bfa0855..d71a2b1bbd 100644 --- a/system/physmem.c +++ b/system/physmem.c @@ -1534,18 +1534,6 @@ static ram_addr_t find_ram_offset(ram_addr_t size) return offset; } =20 -static unsigned long last_ram_page(void) -{ - RAMBlock *block; - ram_addr_t last =3D 0; - - RCU_READ_LOCK_GUARD(); - RAMBLOCK_FOREACH(block) { - last =3D MAX(last, block->offset + block->max_length); - } - return last >> TARGET_PAGE_BITS; -} - static void qemu_ram_setup_dump(void *addr, ram_addr_t size) { int ret; @@ -1799,13 +1787,11 @@ void qemu_ram_msync(RAMBlock *block, ram_addr_t sta= rt, ram_addr_t length) } =20 /* Called with ram_list.mutex held */ -static void dirty_memory_extend(ram_addr_t old_ram_size, - ram_addr_t new_ram_size) +static void dirty_memory_extend(ram_addr_t new_ram_size) { - ram_addr_t old_num_blocks =3D DIV_ROUND_UP(old_ram_size, - DIRTY_MEMORY_BLOCK_SIZE); - ram_addr_t new_num_blocks =3D DIV_ROUND_UP(new_ram_size, - DIRTY_MEMORY_BLOCK_SIZE); + unsigned int old_num_blocks =3D ram_list.num_dirty_blocks; + unsigned int new_num_blocks =3D DIV_ROUND_UP(new_ram_size, + DIRTY_MEMORY_BLOCK_SIZE); int i; =20 /* Only need to extend if block count increased */ @@ -1837,6 +1823,8 @@ static void dirty_memory_extend(ram_addr_t old_ram_si= ze, g_free_rcu(old_blocks, rcu); } } + + ram_list.num_dirty_blocks =3D new_num_blocks; } =20 static void ram_block_add(RAMBlock *new_block, Error **errp) @@ -1846,11 +1834,9 @@ static void ram_block_add(RAMBlock *new_block, Error= **errp) RAMBlock *block; RAMBlock *last_block =3D NULL; bool free_on_error =3D false; - ram_addr_t old_ram_size, new_ram_size; + ram_addr_t ram_size; Error *err =3D NULL; =20 - old_ram_size =3D last_ram_page(); - qemu_mutex_lock_ramlist(); new_block->offset =3D find_ram_offset(new_block->max_length); =20 @@ -1901,11 +1887,8 @@ static void ram_block_add(RAMBlock *new_block, Error= **errp) } } =20 - new_ram_size =3D MAX(old_ram_size, - (new_block->offset + new_block->max_length) >> TARGET_PAGE_B= ITS); - if (new_ram_size > old_ram_size) { - dirty_memory_extend(old_ram_size, new_ram_size); - } + ram_size =3D (new_block->offset + new_block->max_length) >> TARGET_PAG= E_BITS; + dirty_memory_extend(ram_size); /* Keep the list sorted from biggest to smallest block. Unlike QTAILQ, * QLIST (which has an RCU-friendly variant) does not have insertion at * tail, so save the last element in last_block. --=20 2.39.5