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Thu, 02 Apr 2026 08:45:47 -0700 (PDT) Received: from milan ([2001:9b1:d5a0:a500::24b]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-5a2c6c951a6sm750289e87.10.2026.04.02.08.45.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 02 Apr 2026 08:45:46 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Thu, 2 Apr 2026 17:45:44 +0200 To: Qing Wang Cc: Andrew Morton , Uladzislau Rezki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, syzbot+37b7f6cd519f7fb8d32a@syzkaller.appspotmail.com Subject: Re: [PATCH] mm/vmalloc: fix KMSAN uninit-value warning in decay_va_pool_node() Message-ID: References: <20260402081413.1896640-1-wangqing7171@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260402081413.1896640-1-wangqing7171@gmail.com> X-Rspamd-Queue-Id: A4C2F18000E X-Stat-Signature: 6nuwm3tga6xm5nhp73shikyrn61rs8xp X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1775144749-293031 X-HE-Meta: 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 eZ/0lfpp 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Apr 02, 2026 at 04:14:13PM +0800, Qing Wang wrote: > KMSAN reported an uninit-value warning when accessing vmap_area->list > in decay_va_pool_node(): > > BUG: KMSAN: uninit-value in __list_del_entry_valid include/linux/list.h:-1 [inline] > BUG: KMSAN: uninit-value in __list_del_entry include/linux/list.h:223 [inline] > BUG: KMSAN: uninit-value in list_del_init include/linux/list.h:295 [inline] > BUG: KMSAN: uninit-value in decay_va_pool_node+0xf78/0x1dd0 mm/vmalloc.c:2255 > > Uninit was created at: > kmem_cache_alloc_node_noprof+0x3cd/0x12d0 mm/slub.c:4918 > alloc_vmap_area+0x327/0x2e30 mm/vmalloc.c:2065 > > The root cause is that if node_alloc() fail and the va is allocated via > kmem_cache_alloc_node() by alloc_vmap_area(), va->list will be uninitialized. > > Fix this by explicitly initializing va->list after allocation. > > Reported-by: syzbot+37b7f6cd519f7fb8d32a@syzkaller.appspotmail.com > Closes: https://syzkaller.appspot.com/bug?extid=37b7f6cd519f7fb8d32a > I can not access two above links. Are they valid? I would like to have a look at report. > Signed-off-by: Qing Wang > --- > mm/vmalloc.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 61caa55a4402..8aebbb51e178 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -2071,6 +2071,7 @@ static struct vmap_area *alloc_vmap_area(unsigned long size, > * to avoid false negatives. > */ > kmemleak_scan_area(&va->rb_node, SIZE_MAX, gfp_mask); > + INIT_LIST_HEAD(&va->list); > } > va->list does not require to be initialized. Because: spin_lock(&vn->busy.lock); insert_vmap_area(va, &vn->busy.root, &vn->busy.head); spin_unlock(&vn->busy.lock); when a node is inserted into list_head, its next/prev pointers are properly set by the list_add(). Or, am i missing something? -- Uladzislau Rezki