Messages in this thread | | | Date | Tue, 17 Oct 2023 09:35:39 +0200 | Subject | Re: [PATCH] x86/mm: drop 4MB restriction on minimal NUMA node size | From | David Hildenbrand <> |
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On 17.10.23 09:28, David Hildenbrand wrote: > On 17.10.23 08:22, Mike Rapoport wrote: >> From: "Mike Rapoport (IBM)" <rppt@kernel.org> >> >> Qi Zheng reports crashes in a production environment and provides a >> simplified example as a reproducer: >> >> For example, if we use qemu to start a two NUMA node kernel, >> one of the nodes has 2M memory (less than NODE_MIN_SIZE), >> and the other node has 2G, then we will encounter the >> following panic: >> >> [ 0.149844] BUG: kernel NULL pointer dereference, address: 0000000000000000 >> [ 0.150783] #PF: supervisor write access in kernel mode >> [ 0.151488] #PF: error_code(0x0002) - not-present page >> <...> >> [ 0.156056] RIP: 0010:_raw_spin_lock_irqsave+0x22/0x40 >> <...> >> [ 0.169781] Call Trace: >> [ 0.170159] <TASK> >> [ 0.170448] deactivate_slab+0x187/0x3c0 >> [ 0.171031] ? bootstrap+0x1b/0x10e >> [ 0.171559] ? preempt_count_sub+0x9/0xa0 >> [ 0.172145] ? kmem_cache_alloc+0x12c/0x440 >> [ 0.172735] ? bootstrap+0x1b/0x10e >> [ 0.173236] bootstrap+0x6b/0x10e >> [ 0.173720] kmem_cache_init+0x10a/0x188 >> [ 0.174240] start_kernel+0x415/0x6ac >> [ 0.174738] secondary_startup_64_no_verify+0xe0/0xeb >> [ 0.175417] </TASK> >> [ 0.175713] Modules linked in: >> [ 0.176117] CR2: 0000000000000000 >> >> The crashes happen because of inconsistency between nodemask that has >> nodes with less than 4MB as memoryless and the actual memory fed into >> core mm. >> >> The commit 9391a3f9c7f1 ("[PATCH] x86_64: Clear more state when ignoring >> empty node in SRAT parsing") that introduced minimal size of a NUMA node >> does not explain why a node size cannot be less than 4MB and what boot >> failures this restriction might fix. >> >> Since then a lot has changed and core mm won't confuse badly about small >> node sizes. >> >> Drop the limitation for the minimal node size. >> >> Reported-by: Qi Zheng <zhengqi.arch@bytedance.com> >> Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org> >> Acked-by: David Hildenbrand <david@redhat.com> >> Acked-by: Michal Hocko <mhocko@suse.com> >> Link: https://lore.kernel.org/all/20230212110305.93670-1-zhengqi.arch@bytedance.com/ > > That's just a resend I assume? Or has anything changed?
Saw the other mail now, so just a resend.
-- Cheers,
David / dhildenb
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