Commit d52c9750f1 ("coresight: reset "enable_sink" flag when need be") caused a kernel panic because of the using of an invalid value: after 'for_each_cpu(cpu, mask)', value of local variable 'cpu' become invalid, causes following 'cpu_to_node' access invalid memory area. This patch brings the deleted 'cpu = cpumask_first(mask)' back. Panic log: $ perf record -e cs_etm// ls Unable to handle kernel paging request at virtual address fffe801804af4f10 pgd = ffff8017ce031600 [fffe801804af4f10] *pgd=0000000000000000, *pud=0000000000000000 Internal error: Oops: 96000004 [#1] SMP Modules linked in: CPU: 33 PID: 1619 Comm: perf Not tainted 4.7.1+ #16 Hardware name: Huawei Taishan 2280 /CH05TEVBA, BIOS 1.10 11/24/2016 task: ffff8017cb0c8400 ti: ffff8017cb154000 task.ti: ffff8017cb154000 PC is at tmc_alloc_etf_buffer+0x60/0xd4 LR is at tmc_alloc_etf_buffer+0x44/0xd4 pc : [<ffff000008633df8>] lr : [<ffff000008633ddc>] pstate: 60000145 sp : ffff8017cb157b40 x29: ffff8017cb157b40 x28: 0000000000000000 ...skip... 7a60: ffff000008c64dc8 0000000000000006 0000000000000253 ffffffffffffffff 7a80: 0000000000000000 0000000000000000 ffff0000080872cc 0000000000000001 [<ffff000008633df8>] tmc_alloc_etf_buffer+0x60/0xd4 [<ffff000008632b9c>] etm_setup_aux+0x1dc/0x1e8 [<ffff00000816eed4>] rb_alloc_aux+0x2b0/0x338 [<ffff00000816a5e4>] perf_mmap+0x414/0x568 [<ffff0000081ab694>] mmap_region+0x324/0x544 [<ffff0000081abbe8>] do_mmap+0x334/0x3e0 [<ffff000008191150>] vm_mmap_pgoff+0xa4/0xc8 [<ffff0000081a9a30>] SyS_mmap_pgoff+0xb0/0x22c [<ffff0000080872e4>] sys_mmap+0x18/0x28 [<ffff0000080843f0>] el0_svc_naked+0x24/0x28 Code: 912040a5 d0001c00 f873d821 911c6000 (b8656822) ---[ end trace 98933da8f92b0c9a ]--- Signed-off-by: Wang Nan <wangnan0@huawei.com> Cc: Xia Kaixu <xiakaixu@huawei.com> Cc: Li Zefan <lizefan@huawei.com> Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org Fixes: d52c9750f1 ("coresight: reset "enable_sink" flag when need be") Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> Cc: stable <stable@vger.kernel.org> # 4.10 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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