From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 631AC315785; Mon, 4 May 2026 14:19:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777904352; cv=none; b=hr5fk0g5ybDu9hL/ZAw2HmYA/be9COIySrxfA1AF3HV53kO0VSd0qjgxFWBeWme2lsClHd5p/5KqNU2szXj0VBc/XhVvmR3sXxPSCEUzxR9twvNtfrMyf1OtJjoD2H7kfiRLvAV9Nr6DyGyQmn+HfCKEWBl5ywPq+7Hw0j99crA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777904352; c=relaxed/simple; bh=JHAwbQjf+H6aZQl69lHPOT7vY6jZhgMU1CZ5ADXFoec=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cY7b99U6yZUP1dFOGewZQRhrRgDI2rTpSRF3nB55hEIBAjhnES6J2r4AFz3Axmnsq+wI9J/I9oS/iouQQ3CTGPW3X0lb2FOY1izf8cjfJqddHhGtG6r3bb3VAdhOQwhTKzcGTh+ZMb0VRB4NPpeOVreJhsotb5Kv/QKcFnTvi8o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=gHPpHvzC; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="gHPpHvzC" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EE1E4C2BCB8; Mon, 4 May 2026 14:19:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1777904352; bh=JHAwbQjf+H6aZQl69lHPOT7vY6jZhgMU1CZ5ADXFoec=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gHPpHvzCTrQ/RZmyZtlG0AWIexWuSw7JBzsNA+TJfnL96y2QXT3HELwfK+YOfZAAt M7rDKS2Qyf9Hj8aPb3f93fgdpKrZ5PSpb5Q3Qg3e38Ah8uvy8hkfr6fQsguhqqdxh9 BDv+8kFbFPKR6poF5kb4NCPeDqysnjZF1i+dhiio= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Harry Yoo (Oracle)" , "Vlastimil Babka (SUSE)" Subject: [PATCH 6.18 272/275] mm/page_alloc: return NULL early from alloc_frozen_pages_nolock() in NMI on UP Date: Mon, 4 May 2026 15:53:32 +0200 Message-ID: <20260504135153.136894128@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260504135142.929052779@linuxfoundation.org> References: <20260504135142.929052779@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Harry Yoo (Oracle) commit 620b46ed6ae17c8438d889c8c0cfddab36a1476c upstream. On UP kernels (!CONFIG_SMP), spin_trylock() is a no-op that unconditionally succeeds even when the lock is already held. As a result, alloc_frozen_pages_nolock() called from NMI context can re-enter rmqueue() and acquire the zone lock that the interrupted context is already holding, corrupting the freelists. With CONFIG_DEBUG_SPINLOCK on UP, the following BUG is triggered with the slub_kunit test module: BUG: spinlock trylock failure on UP on CPU#0, kunit_try_catch/243 [...] Call Trace: dump_stack_lvl+0x3f/0x60 do_raw_spin_trylock+0x41/0x50 _raw_spin_trylock+0x24/0x50 rmqueue.isra.0+0x2a9/0xa70 get_page_from_freelist+0xeb/0x450 alloc_frozen_pages_nolock_noprof+0x111/0x1e0 allocate_slab+0x42a/0x500 ___slab_alloc+0xa7/0x4c0 kmalloc_nolock_noprof+0x164/0x310 [...] Fix this by returning NULL early when invoked from NMI on a UP kernel. Link: https://lore.kernel.org/linux-mm/ad_cqe51pvr1WaDg@hyeyoo Cc: stable@vger.kernel.org Fixes: d7242af86434 ("mm: Introduce alloc_frozen_pages_nolock()") Signed-off-by: Harry Yoo (Oracle) Link: https://patch.msgid.link/20260427-nolock-api-fix-v2-1-a6b83a92d9a4@kernel.org Signed-off-by: Vlastimil Babka (SUSE) Signed-off-by: Greg Kroah-Hartman --- mm/page_alloc.c | 5 +++++ 1 file changed, 5 insertions(+) --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7641,6 +7641,11 @@ struct page *alloc_frozen_pages_nolock_n */ if (IS_ENABLED(CONFIG_PREEMPT_RT) && (in_nmi() || in_hardirq())) return NULL; + + /* On UP, spin_trylock() always succeeds even when it is locked */ + if (!IS_ENABLED(CONFIG_SMP) && in_nmi()) + return NULL; + if (!pcp_allowed_order(order)) return NULL;