There is a kernel panic caused by __alloc_pages() accessing uninitialized NODE_DATA(nid). Uninitialized node data exists during the time when CPU with memoryless node was added but not onlined yet. Panic can be easy reproduced by disabling udev rule for automatic onlining hot added CPU followed by CPU with memoryless node hot add.
This is a panic caused by percpu code doing allocations for all possible CPUs and hitting this issue:
CPU2 has been hot-added BUG: unable to handle page fault for address: 0000000000001608 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 0 P4D 0 Oops: 0000 [#1] SMP PTI CPU: 0 PID: 1 Comm: systemd Tainted: G E 5.15.0-rc7+ #11 Hardware name: VMware, Inc. VMware7,1/440BX Desktop Reference Platform, BIOS VMW
RIP: 0010:__alloc_pages+0x127/0x290 Code: 4c 89 f0 5b 41 5c 41 5d 41 5e 41 5f 5d c3 44 89 e0 48 8b 55 b8 c1 e8 0c 83 e0 01 88 45 d0 4c 89 c8 48 85 d2 0f 85 1a 01 00 00 <45> 3b 41 08 0f 82 10 01 00 00 48 89 45 c0 48 8b 00 44 89 e2 81 e2 RSP: 0018:ffffc900006f3bc8 EFLAGS: 00010246 RAX: 0000000000001600 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000cc2 RBP: ffffc900006f3c18 R08: 0000000000000001 R09: 0000000000001600 R10: ffffc900006f3a40 R11: ffff88813c9fffe8 R12: 0000000000000cc2 R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000cc2 FS: 00007f27ead70500(0000) GS:ffff88807ce00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000001608 CR3: 000000000582c003 CR4: 00000000001706b0 Call Trace: pcpu_alloc_pages.constprop.0+0xe4/0x1c0 pcpu_populate_chunk+0x33/0xb0 pcpu_alloc+0x4d3/0x6f0 __alloc_percpu_gfp+0xd/0x10 alloc_mem_cgroup_per_node_info+0x54/0xb0 mem_cgroup_alloc+0xed/0x2f0 mem_cgroup_css_alloc+0x33/0x2f0 css_create+0x3a/0x1f0 cgroup_apply_control_enable+0x12b/0x150 cgroup_mkdir+0xdd/0x110 kernfs_iop_mkdir+0x4f/0x80 vfs_mkdir+0x178/0x230 do_mkdirat+0xfd/0x120 __x64_sys_mkdir+0x47/0x70 ? syscall_exit_to_user_mode+0x21/0x50 do_syscall_64+0x43/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae
Node can be in one of the following states: 1. not present (nid == NUMA_NO_NODE) 2. present, but offline (nid > NUMA_NO_NODE, node_online(nid) == 0, NODE_DATA(nid) == NULL) 3. present and online (nid > NUMA_NO_NODE, node_online(nid) > 0, NODE_DATA(nid) != NULL)
alloc_page_{bulk_array}node() functions verify for nid validity only and do not check if nid is online. Enhanced verification check allows to handle page allocation when node is in 2nd state.
Signed-off-by: Alexey Makhalov amakhalov@vmware.com Cc: Andrew Morton akpm@linux-foundation.org Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org Cc: stable@vger.kernel.org --- include/linux/gfp.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/include/linux/gfp.h b/include/linux/gfp.h index 55b2ec1f9..34a5a7def 100644 --- a/include/linux/gfp.h +++ b/include/linux/gfp.h @@ -551,7 +551,8 @@ alloc_pages_bulk_array(gfp_t gfp, unsigned long nr_pages, struct page **page_arr static inline unsigned long alloc_pages_bulk_array_node(gfp_t gfp, int nid, unsigned long nr_pages, struct page **page_array) { - if (nid == NUMA_NO_NODE) + if (nid == NUMA_NO_NODE || (!node_online(nid) && + !(gfp & __GFP_THISNODE))) nid = numa_mem_id();
return __alloc_pages_bulk(gfp, nid, NULL, nr_pages, NULL, page_array); @@ -578,7 +579,8 @@ __alloc_pages_node(int nid, gfp_t gfp_mask, unsigned int order) static inline struct page *alloc_pages_node(int nid, gfp_t gfp_mask, unsigned int order) { - if (nid == NUMA_NO_NODE) + if (nid == NUMA_NO_NODE || (!node_online(nid) && + !(gfp_mask & __GFP_THISNODE))) nid = numa_mem_id();
return __alloc_pages_node(nid, gfp_mask, order);