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axiqiaIngo Molnar
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Ingo Molnar
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perf/core: Bail out early if the request AUX area is out of bound
When perf-record with a large AUX area, e.g 4GB, it fails with: #perf record -C 0 -m ,4G -e arm_spe_0// -- sleep 1 failed to mmap with 12 (Cannot allocate memory) and it reveals a WARNING with __alloc_pages(): ------------[ cut here ]------------ WARNING: CPU: 44 PID: 17573 at mm/page_alloc.c:5568 __alloc_pages+0x1ec/0x248 Call trace: __alloc_pages+0x1ec/0x248 __kmalloc_large_node+0xc0/0x1f8 __kmalloc_node+0x134/0x1e8 rb_alloc_aux+0xe0/0x298 perf_mmap+0x440/0x660 mmap_region+0x308/0x8a8 do_mmap+0x3c0/0x528 vm_mmap_pgoff+0xf4/0x1b8 ksys_mmap_pgoff+0x18c/0x218 __arm64_sys_mmap+0x38/0x58 invoke_syscall+0x50/0x128 el0_svc_common.constprop.0+0x58/0x188 do_el0_svc+0x34/0x50 el0_svc+0x34/0x108 el0t_64_sync_handler+0xb8/0xc0 el0t_64_sync+0x1a4/0x1a8 'rb->aux_pages' allocated by kcalloc() is a pointer array which is used to maintains AUX trace pages. The allocated page for this array is physically contiguous (and virtually contiguous) with an order of 0..MAX_ORDER. If the size of pointer array crosses the limitation set by MAX_ORDER, it reveals a WARNING. So bail out early with -ENOMEM if the request AUX area is out of bound, e.g.: #perf record -C 0 -m ,4G -e arm_spe_0// -- sleep 1 failed to mmap with 12 (Cannot allocate memory) Signed-off-by: Shuai Xue <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
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kernel/events/ring_buffer.c

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Original file line numberDiff line numberDiff line change
@@ -700,6 +700,12 @@ int rb_alloc_aux(struct perf_buffer *rb, struct perf_event *event,
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watermark = 0;
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}
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/*
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* kcalloc_node() is unable to allocate buffer if the size is larger
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* than: PAGE_SIZE << MAX_ORDER; directly bail out in this case.
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*/
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if (get_order((unsigned long)nr_pages * sizeof(void *)) > MAX_ORDER)
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return -ENOMEM;
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rb->aux_pages = kcalloc_node(nr_pages, sizeof(void *), GFP_KERNEL,
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node);
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if (!rb->aux_pages)

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