From patchwork Tue Mar 4 15:04:37 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ryan Roberts X-Patchwork-Id: 14000970 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id ED357C282D2 for ; Tue, 4 Mar 2025 15:35:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=zq+cpplVIbdafYmKh04Zm3BYxIpGtlL4VcJXVKSI9kY=; b=P6nVrX3zxVnGwel4ICkiJb/FM/ YaEoFj6pUOcIelehlm2cqZFx/CTxS3P3ku+yaZAm8zwVVvBjYvfyUohOKQg09NGkrys07e+PdKKmB v/0ngP33dbBytDM/u2SHSFuERLWdRNfEOduKzxW3IBn/4Iu68m5/+nyYbVJntINy+SkrkM7d9p3Bu IW04CoxuvG9GoiuH1/H1wXpkSujqzjafIj3J1lXbib7I3QV/6e3A0K3FVqdfv+i4rrKBbA8vyczB0 YBv27i2ZDRsqomK72/ExXCf6yKW76I7fl14uHfVqEkhAl8U5UZ3usnAwaxFeqN6CkVsKwIrnbDyI5 ppQVsA7A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tpUIW-00000005Eh5-2WTC; Tue, 04 Mar 2025 15:35:08 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tpTpW-000000057Xj-1Qg6 for linux-arm-kernel@lists.infradead.org; Tue, 04 Mar 2025 15:05:11 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B52451007; Tue, 4 Mar 2025 07:05:23 -0800 (PST) Received: from e125769.cambridge.arm.com (e125769.cambridge.arm.com [10.1.196.27]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2EEE23F66E; Tue, 4 Mar 2025 07:05:08 -0800 (PST) From: Ryan Roberts To: Catalin Marinas , Will Deacon , Pasha Tatashin , Andrew Morton , Uladzislau Rezki , Christoph Hellwig , David Hildenbrand , "Matthew Wilcox (Oracle)" , Mark Rutland , Anshuman Khandual , Alexandre Ghiti , Kevin Brodsky Cc: Ryan Roberts , linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 07/11] mm/vmalloc: Warn on improper use of vunmap_range() Date: Tue, 4 Mar 2025 15:04:37 +0000 Message-ID: <20250304150444.3788920-8-ryan.roberts@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250304150444.3788920-1-ryan.roberts@arm.com> References: <20250304150444.3788920-1-ryan.roberts@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250304_070510_425393_B923F2EE X-CRM114-Status: GOOD ( 13.79 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org A call to vmalloc_huge() may cause memory blocks to be mapped at pmd or pud level. But it is possible to subsequently call vunmap_range() on a sub-range of the mapped memory, which partially overlaps a pmd or pud. In this case, vmalloc unmaps the entire pmd or pud so that the no-overlapping portion is also unmapped. Clearly that would have a bad outcome, but it's not something that any callers do today as far as I can tell. So I guess it's just expected that callers will not do this. However, it would be useful to know if this happened in future; let's add a warning to cover the eventuality. Reviewed-by: Anshuman Khandual Reviewed-by: Catalin Marinas Signed-off-by: Ryan Roberts --- mm/vmalloc.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index a6e7acebe9ad..fcdf67d5177a 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -374,8 +374,10 @@ static void vunmap_pmd_range(pud_t *pud, unsigned long addr, unsigned long end, if (cleared || pmd_bad(*pmd)) *mask |= PGTBL_PMD_MODIFIED; - if (cleared) + if (cleared) { + WARN_ON(next - addr < PMD_SIZE); continue; + } if (pmd_none_or_clear_bad(pmd)) continue; vunmap_pte_range(pmd, addr, next, mask); @@ -399,8 +401,10 @@ static void vunmap_pud_range(p4d_t *p4d, unsigned long addr, unsigned long end, if (cleared || pud_bad(*pud)) *mask |= PGTBL_PUD_MODIFIED; - if (cleared) + if (cleared) { + WARN_ON(next - addr < PUD_SIZE); continue; + } if (pud_none_or_clear_bad(pud)) continue; vunmap_pmd_range(pud, addr, next, mask);