From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-143.mta1.migadu.com [95.215.58.143]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A4F2644C4FF for ; Fri, 9 Oct 2026 06:36:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.143 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791527769; cv=none; b=QtgRYHE4pNWfxLg0Q22zMJ60X/xozqnyvn7qf/5yxIdAPriFt/RIlLa8UIPH4+shQX8idi+8YMgDe4rphaAuYWjhp1ud8I/4oUMmfP/O2wJU76surzpsiqfVWDEouENNjGZGkj2+yhVWVsV5h+lqptP4pvw3CwelWdrV6dbYN+Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791527769; c=relaxed/simple; bh=Lh2LMrtSYDDnCgnAv7ysw9EHYWIC+fUbykvCTSebHms=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=jWQ+DBtgc/LMjuv6L/TKjrdSRm8A6HxUIy4sw9NjZrzvUYxK1HAyCaXu9teWky5gYdJ6/S+oYDAGeLVQ9neSntAf16ZiYDGJMX1Mj8cK85V9z2SJ36ultpaSgowqAS3Z02nGxJrscqBu4NE7A7ZpHPpjDwzmNdbCNiDwXr2pggo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=namjizhP; arc=none smtp.client-ip=95.215.58.143 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="namjizhP" X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=Lh2LMrtSYDDnCgnAv7ysw9EHYWIC+fUbykvCTSebHms=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1791527765; v=1; x=1792132565; b=namjizhPyYvj8AmyunUzLnhmSOznkMMx52v0vH2cDMD2zl2bZvwPfDlzgTyXP7aHZH6x2TkB 84qSrfZMOBc/hCzdQ12u3E7O98vYj1Uo+lOiKHBN2N2CZh91eLR/grg1ukE2aN3fYFL83ReEsYz vxUJP3sVSl5kKK3kO9sXCh+E= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id bf8d544524139af5; Fri, 09 Oct 2026 06:36:05 +0000 X-Mizu-Trace-ID: bf8d544524139af5 X-Migadu-Flow: FLOW_OUT From: Hao Ge To: Suren Baghdasaryan , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , "Ritesh Harjani (IBM)" , Shrikanth Hegde , Alexander Potapenko , Marco Elver , Dmitry Vyukov , Andrew Morton , Dennis Zhou , Tejun Heo , Christoph Lameter , Uladzislau Rezki Cc: Hao Ge , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com, linux-mm@kvack.org, Sashiko Subject: [RFC PATCH 2/4] mm/vmalloc: undo partial mappings inside the mapping functions Date: Fri, 9 Oct 2026 14:36:17 +0800 Message-Id: <20261009063619.112313-3-hao.ge@linux.dev> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20261009063619.112313-1-hao.ge@linux.dev> References: <20261009063619.112313-1-hao.ge@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit __vmap_pages_range_noflush() and friends can install some PTEs before failing and leave them mapped, and the kernel callers do not agree on who cleans them up. pcpu_map_pages() and kmsan_ioremap_page_range() roll back what they mapped before the failure, while vm_module_tags_populate() and the __GFP_NOFAIL retry loop in __vmalloc_area_node() rely on the mapping functions cleaning up and do not call anything like vunmap_range() themselves. When the same range is mapped again, the attempt hits the leftovers and fails, with a BUG() in vmap_pte_range() for huge mappings and a warning on the small-page path. After discussing with Suren and Ulad, we decided to put the rollback into the entry points of the vmap API rather than into every low-level helper. __vmap_pages_range_noflush() undoes the whole range it was asked to map when it fails, and vmap_page_range() undoes its range for the ioremap-style mappings. The rollback is __vunmap_range_noflush(), it only clears the PTEs, no TLB flush, nothing has touched these mappings. vmap_pages_range_noflush() drops the KMSAN metadata when the data mapping fails, and an empty range bails out with -EINVAL now, which used to BUG_ON() on the small-page path and map nothing at all on the huge-page one. Reported-by: Sashiko Suggested-by: Uladyslau Rezki Signed-off-by: Hao Ge --- mm/vmalloc.c | 44 ++++++++++++++++++++++++++++++++------------ 1 file changed, 32 insertions(+), 12 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index db669103dc66..e1b376f57dd2 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -363,6 +363,9 @@ int vmap_page_range(unsigned long addr, unsigned long end, if (!err) err = kmsan_ioremap_page_range(addr, end, phys_addr, prot, ioremap_max_page_shift); + if (err) + __vunmap_range_noflush(addr, end); + return err; } @@ -683,27 +686,35 @@ int __vmap_pages_range_noflush(unsigned long addr, unsigned long end, pgprot_t prot, struct page **pages, unsigned int page_shift) { unsigned int i, nr = (end - addr) >> PAGE_SHIFT; + unsigned long start = addr; + int err = 0; + + if (WARN_ON_ONCE(addr >= end)) + return -EINVAL; if (WARN_ON_ONCE(page_shift < PAGE_SHIFT)) return -EINVAL; if (!IS_ENABLED(CONFIG_HAVE_ARCH_HUGE_VMALLOC) || - page_shift == PAGE_SHIFT) - return vmap_small_pages_range_noflush(addr, end, prot, pages); - - for (i = 0; i < nr; i += 1U << (page_shift - PAGE_SHIFT)) { - int err; - - err = vmap_range_noflush(addr, addr + (1UL << page_shift), + page_shift == PAGE_SHIFT) { + err = vmap_small_pages_range_noflush(addr, end, prot, pages); + } else { + for (i = 0; i < nr; i += 1U << (page_shift - PAGE_SHIFT)) { + err = vmap_range_noflush(addr, addr + (1UL << page_shift), page_to_phys(pages[i]), prot, page_shift); - if (err) - return err; + if (err) + break; - addr += 1UL << page_shift; + addr += 1UL << page_shift; + } } - return 0; + /* Undo the PTEs installed before the failure. */ + if (err) + __vunmap_range_noflush(start, end); + + return err; } int vmap_pages_range_noflush(unsigned long addr, unsigned long end, @@ -715,7 +726,16 @@ int vmap_pages_range_noflush(unsigned long addr, unsigned long end, if (ret) return ret; - return __vmap_pages_range_noflush(addr, end, prot, pages, page_shift); + + ret = __vmap_pages_range_noflush(addr, end, prot, pages, page_shift); + /* + * The page tables undo themselves on failure. Tear down the + * metadata that was fully set up before the mapping failed. + */ + if (ret) + kmsan_vunmap_range_noflush(addr, end); + + return ret; } static int __vmap_pages_range(unsigned long addr, unsigned long end, -- 2.25.1