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BUG: KCSAN: data-race in purge_fragmented_blocks_allcpus / vm_map_ram

write to 0xffff88809246f490 of 8 bytes by task 3573 on cpu 1:
 vb_alloc mm/vmalloc.c:1646 [inline]
 vm_map_ram+0x1eb/0x14f0 mm/vmalloc.c:1828
 ion_heap_clear_pages+0x30/0x80 drivers/staging/android/ion/ion_heap.c:102
 ion_heap_sglist_zero+0x147/0x180 drivers/staging/android/ion/ion_heap.c:123
 ion_heap_buffer_zero+0x91/0xc0 drivers/staging/android/ion/ion_heap.c:145
 ion_system_heap_free+0x11b/0x120 drivers/staging/android/ion/ion_system_heap.c:163
 ion_buffer_destroy+0xc1/0x190 drivers/staging/android/ion/ion.c:93
 ion_heap_deferred_free+0x1c8/0x330 drivers/staging/android/ion/ion_heap.c:239
 kthread+0x1cb/0x1f0 kernel/kthread.c:255
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

read to 0xffff88809246f490 of 8 bytes by task 11381 on cpu 0:
 purge_fragmented_blocks mm/vmalloc.c:1581 [inline]
 purge_fragmented_blocks_allcpus+0x2dc/0x510 mm/vmalloc.c:1611
 _vm_unmap_aliases.part.0+0x1cb/0x250 mm/vmalloc.c:1745
 _vm_unmap_aliases mm/vmalloc.c:1715 [inline]
 vm_unmap_aliases+0x45/0x50 mm/vmalloc.c:1769
 change_page_attr_set_clr+0x127/0x5c0 arch/x86/mm/pat/set_memory.c:1720
 change_page_attr_clear arch/x86/mm/pat/set_memory.c:1777 [inline]
 set_memory_ro+0x38/0x50 arch/x86/mm/pat/set_memory.c:1910
 bpf_jit_binary_lock_ro include/linux/filter.h:797 [inline]
 bpf_int_jit_compile+0x7c2/0x952 arch/x86/net/bpf_jit_comp.c:1807
 bpf_prog_select_runtime+0x2f0/0x460 kernel/bpf/core.c:1799
 bpf_prog_load+0x9f5/0xe80 kernel/bpf/syscall.c:2105
 __do_sys_bpf+0xef0/0x29c0 kernel/bpf/syscall.c:3396
 __se_sys_bpf kernel/bpf/syscall.c:3355 [inline]
 __x64_sys_bpf+0x47/0x60 kernel/bpf/syscall.c:3355
 do_syscall_64+0xc7/0x390 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 11381 Comm: syz-executor.0 Not tainted 5.6.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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