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Wed, 14 Feb 2024 15:03:40 -0500 X-MC-Unique: UE3PNMBuOli5idaLMadW9Q-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.rdu2.redhat.com [10.11.54.2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id CA0A43C23FCF; Wed, 14 Feb 2024 20:03:29 +0000 (UTC) Received: from lorien.usersys.redhat.com (unknown [10.39.192.33]) by smtp.corp.redhat.com (Postfix) with ESMTPS id D29F640CD14A; Wed, 14 Feb 2024 20:03:22 +0000 (UTC) Date: Wed, 14 Feb 2024 15:03:18 -0500 From: Phil Auld To: Byungchul Park Cc: 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, linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel_team@skhynix.com, akpm@linux-foundation.org Subject: Re: [PATCH] sched/numa, mm: do not promote folios to nodes not set N_MEMORY Message-ID: <20240214200318.GA74174@lorien.usersys.redhat.com> References: <20240214035355.18335-1-byungchul@sk.com> <20240214123137.GA70927@lorien.usersys.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240214123137.GA70927@lorien.usersys.redhat.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.2 X-Stat-Signature: 3wfbbbhacyuzuomqdemzezei6yyprugu X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: B2D9C80018 X-Rspam-User: X-HE-Tag: 1707941027-878826 X-HE-Meta: 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 a6eO6M+b ZVi6+3Iu138vWxdj9xH84jeMbRcICjbBIg8X+TWiugn62irh35/1hfsAMl/wMVxnTXb6TzUJYAg3bAzFniyKvv3bHPolMd0x+Jb3dohOdLqfh9/xcVmDjVt4cGdfRKLzNkTTXZLQmN63CCaPdGZ8rU/+LP2a1omZWndAOdYSL+KGWhVHrv9RdAvsxh+DQUBW6YI2sIaOha493uFE2eVyyMGtK8/7OcwutS7J2EHBdO4/qGelAGG3ZBzGqbA3udFo0nIsGKkGjmE/Y8H7u+aYNOhDnsj/bH24GMYvHwWiogoXyB8YLsLIucqeuEJVaFJNASz0kf9Hk+wu8mt4= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Feb 14, 2024 at 07:31:37AM -0500 Phil Auld wrote: > Hi, > > On Wed, Feb 14, 2024 at 12:53:55PM +0900 Byungchul Park wrote: > > 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 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:0000000000000000 > > > 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 > > > > > > Modules linked in: > > > CR2: 00000000000033f3 > > > ---[ end trace 0000000000000000 ]--- > > > 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:0000000000000000 > > > 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 > > > note: masim[895] exited with irqs disabled > > I think you could trim the down a little bit. > > > > > > Signed-off-by: Byungchul Park > > Reported-by: hyeongtak.ji@sk.com > > --- > > kernel/sched/fair.c | 17 +++++++++++++++++ > > 1 file changed, 17 insertions(+) > > > > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c > > index d7a3c63a2171..6d215cc85f14 100644 > > --- a/kernel/sched/fair.c > > +++ b/kernel/sched/fair.c > > @@ -1828,6 +1828,23 @@ bool should_numa_migrate_memory(struct task_struct *p, struct folio *folio, > > int dst_nid = cpu_to_node(dst_cpu); > > int last_cpupid, this_cpupid; > > > > + /* > > + * 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. > > + * > > > + * For instance, oops has been observed at CPU2 while qemu'ing: > > + * > > + * {qemu} \ > > + * -numa node,nodeid=0,mem=1G,cpus=0-1 \ > > + * -numa node,nodeid=1,cpus=2-3 \ > > + * -numa node,nodeid=2,mem=8G \ > > + * ... > > This part above should probably be in the commit message not in the code. > The first paragraph of comment is plenty. > > Otherwise, I think the check probably makes sense. > Actually, after looking at the memory.c code I wonder if this check should not be made farther up in the numa migrate machinery. Cheers, Phil > > Cheers, > Phil > > > + */ > > + 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. > > -- > > 2.17.1 > > > > > > -- > > --