From nobody Sun Feb 8 07:52:29 2026 Received: from invmail4.hynix.com (exvmail4.skhynix.com [166.125.252.92]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 83D6015E8B for ; Fri, 16 Feb 2024 07:33:51 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=166.125.252.92 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708068840; cv=none; b=ru0GPkPqkH7wGPlmRidzk5YlLf+bwM735Aijh0FXmUQYa5QSnwpElLPEPd45PqdQLQCJXMKixHicctGE6DEE6MmGYBc/wlIxdOtOzICn9uDpIzHHHhX32zQ2PE5A6gAPxD5scC9dzmHHXkM4QiQ8i5fD6VnHytQ041InQS0QzKA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708068840; c=relaxed/simple; bh=cAH7DMxuXm3UwwG9aeS1vnD0RhVr10jUVfSZVMparjw=; h=From:To:Cc:Subject:Date:Message-Id; b=HnKpub/sw+BS4spwOxJpV7acg0kGwgO8IBwvxWrOX/ZeKqvns2we3vJjJTBmPLwOARIyR6p3Hg5QW7NorJObi3ww2lLoPuiJYlJvmyCskEuDZynFKP/uziHv4AbVouKaTbtDxFWCcv09s8HMGpZbIPWi7rNyTgXlYOB9qp+Kajg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sk.com; spf=pass smtp.mailfrom=sk.com; arc=none smtp.client-ip=166.125.252.92 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sk.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sk.com X-AuditID: a67dfc5b-d6dff70000001748-0a-65cf0fde2f2c From: Byungchul Park To: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel_team@skhynix.com, akpm@linux-foundation.org Subject: [PATCH v2] sched/numa, mm: do not promote folios to nodes not set N_MEMORY Date: Fri, 16 Feb 2024 16:33:40 +0900 Message-Id: <20240216073340.55404-1-byungchul@sk.com> X-Mailer: git-send-email 2.17.1 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrLLMWRmVeSWpSXmKPExsXC9ZZnke49/vOpBs9fSlrMWb+GzeLS46ts FtNfNrJYPJ2wldnibv9UFovLu+awWdxb85/VYvK7Z4wWlw4sYLI43nuAyWJfxwMmi44j35gt th79zu7A67Fm3hpGj5Z9t9g9Fmwq9di8Qstj06dJ7B53ru1h8zgx4zeLx/t9V9k8Np+u9vi8 SS6AK4rLJiU1J7MstUjfLoEr4/X3p4wFJ2Uq+vZMY25gfCPexcjJISFgItF9aS4TjD21bTE7 iM0moC5x48ZP5i5GLg4RgTeMEp3LzrCBJJgF8iRa//eBNQgLBEss2LOWBcRmEVCV2HyyixHE 5hUwlTj84QkzxFB5idUbDoANkhDYwCaxeMFvVoiEpMTBFTdYJjByL2BkWMUolJlXlpuYmWOi l1GZl1mhl5yfu4kRGIjLav9E72D8dCH4EKMAB6MSD++BP2dThVgTy4orcw8xSnAwK4nwTuo9 kyrEm5JYWZValB9fVJqTWnyIUZqDRUmc1+hbeYqQQHpiSWp2ampBahFMlomDU6qBkeG6t7RV z+Lv3zazH5rH8NDrYszfcg9e346DylkSgmFBsUL9R2o5l22qbur+FiKT/WJtTqWcavcpaZZF b8VunJfVuJ6rJqSd4zJZXyNrZ6/b48ivi/0D/6Tue/WibMERQ8X3y20bNrmxM8peW6M84/wT vyfz5BcEv5U/GFaVILaRr7NAcm+uEktxRqKhFnNRcSIA4FVAu0ACAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFprCLMWRmVeSWpSXmKPExsXC5WfdrHuP/3yqwcWj3BZz1q9hs7j0+Cqb xfSXjSwWTydsZba42z+VxeLw3JOsFpd3zWGzuLfmP6vF5HfPGC0uHVjAZHG89wCTxb6OB0wW HUe+MVtsPfqd3YHPY828NYweLftusXss2FTqsXmFlsemT5PYPe5c28PmcWLGbxaP9/uusnks fvGByWPz6WqPz5vkArijuGxSUnMyy1KL9O0SuDJef3/KWHBSpqJvzzTmBsY34l2MnBwSAiYS U9sWs4PYbALqEjdu/GTuYuTiEBF4wyjRuewMG0iCWSBPovV/HxOILSwQLLFgz1oWEJtFQFVi 88kuRhCbV8BU4vCHJ8wQQ+UlVm84wDyBkWMBI8MqRpHMvLLcxMwcU73i7IzKvMwKveT83E2M wLBaVvtn4g7GL5fdDzEKcDAq8fAe+HM2VYg1say4MvcQowQHs5II76TeM6lCvCmJlVWpRfnx RaU5qcWHGKU5WJTEeb3CUxOEBNITS1KzU1MLUotgskwcnFINjNUZnqo/itbvuv1Aeo511C6O i4pX9E2vfo7ekHNjo72qaMARVe4Da5zLNtbPPP7jdMHFTSc9J8hMuNbMs++iudYr3vlf9FYt +7IvRmQGZ9HKKoMG46mWLu47D1eV/D1dfNS0MGX/tTm5Fc3bp3RxBK4XfPV55TY73aDbOyaK TDUu6n9QXLFSRleJpTgj0VCLuag4EQAptKZcJwIAAA== X-CFilter-Loop: Reflected Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Changes from v1: 1. Trim the verbose oops in the commit message. (feedbacked by Phil Auld) 2. Rewrite a comment in code. (feedbacked by Phil Auld) Reported-by: Hyeongtak Ji --->8--- From 6830b59db267a31b78f6f09af12ae0e3132b4bca Mon Sep 17 00:00:00 2001 From: Byungchul Park Date: Fri, 16 Feb 2024 16:26:23 +0900 Subject: [PATCH v2] sched/numa, mm: do not promote folios to nodes not set = N_MEMORY While running qemu with a configuration where some CPUs don't have their local memory and with a kernel numa balancing on, the following oops has been observed. It's because of null pointers of ->zone_pgdat of zones of those nodes that are not initialized properly at booting time. So should avoid nodes not set N_MEMORY from getting promoted. > BUG: unable to handle page fault for address: 00000000000033f3 > #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > PGD 0 P4D 0 > Oops: 0000 [#1] PREEMPT SMP NOPTI > CPU: 2 PID: 895 Comm: masim Not tainted 6.6.0-dirty #255 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS > rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 > RIP: 0010:wakeup_kswapd (./linux/mm/vmscan.c:7812) > Code: (omitted) > RSP: 0000:ffffc90004257d58 EFLAGS: 00010286 > RAX: ffffffffffffffff RBX: ffff88883fff0480 RCX: 0000000000000003 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88883fff0480 > RBP: ffffffffffffffff R08: ff0003ffffffffff R09: ffffffffffffffff > R10: ffff888106c95540 R11: 0000000055555554 R12: 0000000000000003 > R13: 0000000000000000 R14: 0000000000000000 R15: ffff88883fff0940 > FS: 00007fc4b8124740(0000) GS:ffff888827c00000(0000) knlGS:0000000000000= 000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00000000000033f3 CR3: 000000026cc08004 CR4: 0000000000770ee0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > PKRU: 55555554 > Call Trace: > > ? __die > ? page_fault_oops > ? __pte_offset_map_lock > ? exc_page_fault > ? asm_exc_page_fault > ? wakeup_kswapd > migrate_misplaced_page > __handle_mm_fault > handle_mm_fault > do_user_addr_fault > exc_page_fault > asm_exc_page_fault > RIP: 0033:0x55b897ba0808 > Code: (omitted) > RSP: 002b:00007ffeefa821a0 EFLAGS: 00010287 > RAX: 000055b89983acd0 RBX: 00007ffeefa823f8 RCX: 000055b89983acd0 > RDX: 00007fc2f8122010 RSI: 0000000000020000 RDI: 000055b89983acd0 > RBP: 00007ffeefa821a0 R08: 0000000000000037 R09: 0000000000000075 > R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 > R13: 00007ffeefa82410 R14: 000055b897ba5dd8 R15: 00007fc4b8340000 > Signed-off-by: Byungchul Park Reported-by: Hyeongtak Ji --- kernel/sched/fair.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index d7a3c63a2171..859ef78ef72b 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1828,6 +1828,15 @@ bool should_numa_migrate_memory(struct task_struct *= p, struct folio *folio, int dst_nid =3D cpu_to_node(dst_cpu); int last_cpupid, this_cpupid; =20 + /* + * A node of dst_nid might not have its local memory. Promoting + * a folio to the node is meaningless. What's even worse, oops + * can be observed by the null pointer of ->zone_pgdat in + * various points of the code during migration. + */ + if (!node_state(dst_nid, N_MEMORY)) + return false; + /* * The pages in slow memory node should be migrated according * to hot/cold instead of private/shared. --=20 2.17.1