From nobody Wed Dec 17 15:40:00 2025 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) (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 3720D15698B for ; Tue, 9 Jul 2024 12:09:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.187 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720526943; cv=none; b=PdQPD3R0RP/bKKbE/8Rxc/axvuRChYDVf34bOcM8dR7o8Ep2Z7MZIzA2+zPrSOtuWGCuPSQ0S4YOkLOYGH6JH849C+jq6yOXmUAbGEP5zXgHbwxaROcDJi2xCWj8ENYgDD7HjsMfK08ymDinRU348sHQ/FrYkhwc5ftV5dTJQHs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720526943; c=relaxed/simple; bh=RIuJW2HSlWkVuTxGn8EDkvTolj2vv54kHJPwiUvk7so=; h=From:To:CC:Subject:Date:Message-ID:MIME-Version:Content-Type; b=pUyGGT5FGEdD4Y2CIxJSBYvgl+gmXx/AY73yhWA+TQF2pARhDN928eZNmtUMw+D/OdXGMxtoD1edmr6rfiZQ8bl2Me3rqS1eqQdyhoxpqiIp3ThoZKInoKlolFxh2IIXtZZQmH4mImgNV3Kpe2frtDgq6srz1CG9Nq6ijmWsDfo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.187 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.163.252]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4WJKRD3WB5zxVdJ; Tue, 9 Jul 2024 20:04:24 +0800 (CST) Received: from kwepemd200019.china.huawei.com (unknown [7.221.188.193]) by mail.maildlp.com (Postfix) with ESMTPS id 9F2AE180ADD; Tue, 9 Jul 2024 20:08:58 +0800 (CST) Received: from huawei.com (10.173.127.72) by kwepemd200019.china.huawei.com (7.221.188.193) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Tue, 9 Jul 2024 20:08:57 +0800 From: Miaohe Lin To: , , , CC: , , Subject: [PATCH RESEND] mm/hugetlb: fix kernel NULL pointer dereference when migrating hugetlb folio Date: Tue, 9 Jul 2024 20:04:33 +0800 Message-ID: <20240709120433.4136700-1-linmiaohe@huawei.com> X-Mailer: git-send-email 2.33.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemd200019.china.huawei.com (7.221.188.193) Content-Type: text/plain; charset="utf-8" A kernel crash was observed when migrating hugetlb folio: BUG: kernel NULL pointer dereference, address: 0000000000000008 PGD 0 P4D 0 Oops: Oops: 0002 [#1] PREEMPT SMP NOPTI CPU: 0 PID: 3435 Comm: bash Not tainted 6.10.0-rc6-00450-g8578ca01f21f #66 RIP: 0010:__folio_undo_large_rmappable+0x70/0xb0 RSP: 0018:ffffb165c98a7b38 EFLAGS: 00000097 RAX: fffffbbc44528090 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffffa30e000a2800 RSI: 0000000000000246 RDI: ffffa3153ffffcc0 RBP: fffffbbc44528000 R08: 0000000000002371 R09: ffffffffbe4e5868 R10: 0000000000000001 R11: 0000000000000001 R12: ffffa3153ffffcc0 R13: fffffbbc44468000 R14: 0000000000000001 R15: 0000000000000001 FS: 00007f5b3a716740(0000) GS:ffffa3151fc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000008 CR3: 000000010959a000 CR4: 00000000000006f0 Call Trace: __folio_migrate_mapping+0x59e/0x950 __migrate_folio.constprop.0+0x5f/0x120 move_to_new_folio+0xfd/0x250 migrate_pages+0x383/0xd70 soft_offline_page+0x2ab/0x7f0 soft_offline_page_store+0x52/0x90 kernfs_fop_write_iter+0x12c/0x1d0 vfs_write+0x380/0x540 ksys_write+0x64/0xe0 do_syscall_64+0xb9/0x1d0 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f5b3a514887 RSP: 002b:00007ffe138fce68 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 000000000000000c RCX: 00007f5b3a514887 RDX: 000000000000000c RSI: 0000556ab809ee10 RDI: 0000000000000001 RBP: 0000556ab809ee10 R08: 00007f5b3a5d1460 R09: 000000007fffffff R10: 0000000000000000 R11: 0000000000000246 R12: 000000000000000c R13: 00007f5b3a61b780 R14: 00007f5b3a617600 R15: 00007f5b3a616a00 It's because hugetlb folio is passed to __folio_undo_large_rmappable() unexpectedly. large_rmappable flag is imperceptibly set to hugetlb folio since commit f6a8dd98a2ce ("hugetlb: convert alloc_buddy_hugetlb_folio to use a folio"). Then commit be9581ea8c05 ("mm: fix crashes from deferred split racing folio migration") makes folio_migrate_mapping() call folio_undo_large_rmappable() triggering the bug. Fix this issue by clearing large_rmappable flag for hugetlb folios. They don't need that flag set anyway. Fixes: f6a8dd98a2ce ("hugetlb: convert alloc_buddy_hugetlb_folio to use a f= olio") Fixes: be9581ea8c05 ("mm: fix crashes from deferred split racing folio migr= ation") Signed-off-by: Miaohe Lin Cc: --- mm/hugetlb.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 6282dd9e37e3..45fd3bc75332 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2173,6 +2173,9 @@ static struct folio *alloc_buddy_hugetlb_folio(struct= hstate *h, nid =3D numa_mem_id(); retry: folio =3D __folio_alloc(gfp_mask, order, nid, nmask); + /* Ensure hugetlb folio won't have large_rmappable flag set. */ + if (folio) + folio_clear_large_rmappable(folio); =20 if (folio && !folio_ref_freeze(folio, 1)) { folio_put(folio); --=20 2.33.0