From nobody Sat Nov 1 07:24:57 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) client-ip=192.237.175.120; envelope-from=xen-devel-bounces@lists.xenproject.org; helo=lists.xenproject.org; Authentication-Results: mx.zohomail.com; spf=pass (zohomail.com: domain of lists.xenproject.org designates 192.237.175.120 as permitted sender) smtp.mailfrom=xen-devel-bounces@lists.xenproject.org; dmarc=fail(p=reject dis=none) header.from=linux.ibm.com Return-Path: Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) by mx.zohomail.com with SMTPS id 1743153250576476.18501536080487; Fri, 28 Mar 2025 02:14:10 -0700 (PDT) Received: from list by lists.xenproject.org with outflank-mailman.930368.1333055 (Exim 4.92) (envelope-from ) id 1ty5mo-0002qt-QJ; Fri, 28 Mar 2025 09:13:58 +0000 Received: by outflank-mailman (output) from mailman id 930368.1333055; Fri, 28 Mar 2025 09:13:58 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1ty5mo-0002pz-K7; Fri, 28 Mar 2025 09:13:58 +0000 Received: by outflank-mailman (input) for mailman id 930368; Fri, 28 Mar 2025 09:13:57 +0000 Received: from se1-gles-flk1-in.inumbo.com ([94.247.172.50] helo=se1-gles-flk1.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1ty5mn-0001o1-55 for xen-devel@lists.xenproject.org; Fri, 28 Mar 2025 09:13:57 +0000 Received: from li-008a6a4c-3549-11b2-a85c-c5cc2836eea2.ibm.com (unknown [2a02:8070:a484:e780::f9cd]) by se1-gles-flk1.inumbo.com (Halon) with ESMTPS id f6f2a26d-0bb4-11f0-9ffa-bf95429c2676; Fri, 28 Mar 2025 10:13:52 +0100 (CET) Received: from agordeev by li-008a6a4c-3549-11b2-a85c-c5cc2836eea2.ibm.com with local (Exim 4.98.1) (envelope-from ) id 1ty5mY-00000001t9f-1ee8; Fri, 28 Mar 2025 10:13:42 +0100 X-Outflank-Mailman: Message body and most headers restored to incoming version X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list X-Inumbo-ID: f6f2a26d-0bb4-11f0-9ffa-bf95429c2676 From: Alexander Gordeev To: Andrey Ryabinin , Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com, sparclinux@vger.kernel.org, xen-devel@lists.xenproject.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, Hugh Dickins , Nicholas Piggin , Guenter Roeck , Juergen Gross , Jeremy Fitzhardinge Subject: [PATCH 1/4] kasan: Avoid sleepable page allocation from atomic context Date: Fri, 28 Mar 2025 10:13:39 +0100 Message-ID: X-Mailer: git-send-email 2.43.5 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Sender: Alexander Gordeev X-ZM-MESSAGEID: 1743153252252019100 Content-Type: text/plain; charset="utf-8" apply_to_page_range() enters lazy MMU mode and then invokes kasan_populate_vmalloc_pte() callback on each page table walk iteration. The lazy MMU mode may only be entered only under protection of the page table lock. However, the callback can go into sleep when trying to allocate a single page. Change __get_free_page() allocation mode from GFP_KERNEL to GFP_ATOMIC to avoid scheduling out while in atomic context. Signed-off-by: Alexander Gordeev --- mm/kasan/shadow.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c index 88d1c9dcb507..edfa77959474 100644 --- a/mm/kasan/shadow.c +++ b/mm/kasan/shadow.c @@ -301,7 +301,7 @@ static int kasan_populate_vmalloc_pte(pte_t *ptep, unsi= gned long addr, if (likely(!pte_none(ptep_get(ptep)))) return 0; =20 - page =3D __get_free_page(GFP_KERNEL); + page =3D __get_free_page(GFP_ATOMIC); if (!page) return -ENOMEM; =20 --=20 2.45.2