From: Oscar Salvador osalvador@suse.de
mainline inclusion from mainline-v5.18-rc1 commit 1ca75fa7f19d694c58af681fa023295072b03120 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I8EQ3K
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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On x86, prior to ("mm: handle uninitialized numa nodes gracecully"), NUMA nodes could be allocated at three different places.
- numa_register_memblks - init_cpu_to_node - init_gi_nodes
All these calls happen at setup_arch, and have the following order:
setup_arch ... x86_numa_init numa_init numa_register_memblks ... init_cpu_to_node init_memory_less_node alloc_node_data free_area_init_memoryless_node init_gi_nodes init_memory_less_node alloc_node_data free_area_init_memoryless_node
numa_register_memblks() is only interested in those nodes which have memory, so it skips over any memoryless node it founds. Later on, when we have read ACPI's SRAT table, we call init_cpu_to_node() and init_gi_nodes(), which initialize any memoryless node we might have that have either CPU or Initiator affinity, meaning we allocate pg_data_t struct for them and we mark them as ONLINE.
So far so good, but the thing is that after ("mm: handle uninitialized numa nodes gracefully"), we allocate all possible NUMA nodes in free_area_init(), meaning we have a picture like the following:
setup_arch x86_numa_init numa_init numa_register_memblks <-- allocate non-memoryless node x86_init.paging.pagetable_init ... free_area_init free_area_init_memoryless <-- allocate memoryless node init_cpu_to_node alloc_node_data <-- allocate memoryless node with CPU free_area_init_memoryless_node init_gi_nodes alloc_node_data <-- allocate memoryless node with Initiator free_area_init_memoryless_node
free_area_init() already allocates all possible NUMA nodes, but init_cpu_to_node() and init_gi_nodes() are clueless about that, so they go ahead and allocate a new pg_data_t struct without checking anything, meaning we end up allocating twice.
It should be mad clear that this only happens in the case where memoryless NUMA node happens to have a CPU/Initiator affinity.
So get rid of init_memory_less_node() and just set the node online.
Note that setting the node online is needed, otherwise we choke down the chain when bringup_nonboot_cpus() ends up calling __try_online_node()->register_one_node()->... and we blow up in bus_add_device(). As can be seen here:
BUG: kernel NULL pointer dereference, address: 0000000000000060 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC PTI CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.17.0-rc4-1-default+ #45 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.0.0-prebuilt.qemu-project.org 04/4 RIP: 0010:bus_add_device+0x5a/0x140 Code: 8b 74 24 20 48 89 df e8 84 96 ff ff 85 c0 89 c5 75 38 48 8b 53 50 48 85 d2 0f 84 bb 00 004 RSP: 0000:ffffc9000022bd10 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff888100987400 RCX: ffff8881003e4e19 RDX: ffff8881009a5e00 RSI: ffff888100987400 RDI: ffff888100987400 RBP: 0000000000000000 R08: ffff8881003e4e18 R09: ffff8881003e4c98 R10: 0000000000000000 R11: ffff888100402bc0 R12: ffffffff822ceba0 R13: 0000000000000000 R14: ffff888100987400 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff88853fc00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000060 CR3: 000000000200a001 CR4: 00000000001706b0 Call Trace: device_add+0x4c0/0x910 __register_one_node+0x97/0x2d0 __try_online_node+0x85/0xc0 try_online_node+0x25/0x40 cpu_up+0x4f/0x100 bringup_nonboot_cpus+0x4f/0x60 smp_init+0x26/0x79 kernel_init_freeable+0x130/0x2f1 kernel_init+0x17/0x150 ret_from_fork+0x22/0x30
The reason is simple, by the time bringup_nonboot_cpus() gets called, we did not register the node_subsys bus yet, so we crash when bus_add_device() tries to dereference bus()->p.
The following shows the order of the calls:
kernel_init_freeable smp_init bringup_nonboot_cpus ... bus_add_device() <- we did not register node_subsys yet do_basic_setup do_initcalls postcore_initcall(register_node_type); register_node_type subsys_system_register subsys_register bus_register <- register node_subsys bus
Why setting the node online saves us then? Well, simply because __try_online_node() backs off when the node is online, meaning we do not end up calling register_one_node() in the first place.
This is subtle, broken and deserves a deep analysis and thought about how to put this into shape, but for now let us have this easy fix for the leaking memory issue.
[osalvador@suse.de: add comments] Link: https://lkml.kernel.org/r/20220221142649.3457-1-osalvador@suse.de
Link: https://lkml.kernel.org/r/20220218224302.5282-2-osalvador@suse.de Fixes: da4490c958ad ("mm: handle uninitialized numa nodes gracefully") Signed-off-by: Oscar Salvador osalvador@suse.de Acked-by: Michal Hocko mhocko@suse.com Cc: David Hildenbrand david@redhat.com Cc: Rafael Aquini raquini@redhat.com Cc: Dave Hansen dave.hansen@linux.intel.com Cc: Wei Yang richard.weiyang@gmail.com Cc: Dennis Zhou dennis@kernel.org Cc: Alexey Makhalov amakhalov@vmware.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Ma Wupeng mawupeng1@huawei.com --- arch/x86/mm/numa.c | 33 ++++++++++++++++++++------------- include/linux/mm.h | 1 - mm/page_alloc.c | 2 +- 3 files changed, 21 insertions(+), 15 deletions(-)
diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c index 9dc31996c7ed..cfb326e41dc6 100644 --- a/arch/x86/mm/numa.c +++ b/arch/x86/mm/numa.c @@ -739,17 +739,6 @@ void __init x86_numa_init(void) numa_init(dummy_numa_init); }
-static void __init init_memory_less_node(int nid) -{ - /* Allocate and initialize node data. Memory-less node is now online.*/ - alloc_node_data(nid); - free_area_init_memoryless_node(nid); - - /* - * All zonelists will be built later in start_kernel() after per cpu - * areas are initialized. - */ -}
/* * A node may exist which has one or more Generic Initiators but no CPUs and no @@ -767,9 +756,18 @@ void __init init_gi_nodes(void) { int nid;
+ /* + * Exclude this node from + * bringup_nonboot_cpus + * cpu_up + * __try_online_node + * register_one_node + * because node_subsys is not initialized yet. + * TODO remove dependency on node_online + */ for_each_node_state(nid, N_GENERIC_INITIATOR) if (!node_online(nid)) - init_memory_less_node(nid); + node_set_online(nid); }
/* @@ -799,8 +797,17 @@ void __init init_cpu_to_node(void) if (node == NUMA_NO_NODE) continue;
+ /* + * Exclude this node from + * bringup_nonboot_cpus + * cpu_up + * __try_online_node + * register_one_node + * because node_subsys is not initialized yet. + * TODO remove dependency on node_online + */ if (!node_online(node)) - init_memory_less_node(node); + node_set_online(node);
numa_set_node(cpu, node); } diff --git a/include/linux/mm.h b/include/linux/mm.h index a5316ffd4e1f..2ad509486cad 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2402,7 +2402,6 @@ static inline spinlock_t *pud_lock(struct mm_struct *mm, pud_t *pud) }
extern void __init pagecache_init(void); -extern void __init free_area_init_memoryless_node(int nid); extern void free_initmem(void);
/* diff --git a/mm/page_alloc.c b/mm/page_alloc.c index d586c6e6faee..f21365c92a98 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7626,7 +7626,7 @@ static void __init free_area_init_node(int nid) free_area_init_core(pgdat); }
-void __init free_area_init_memoryless_node(int nid) +static void __init free_area_init_memoryless_node(int nid) { free_area_init_node(nid); }