Messages in this thread | | | Date | Mon, 13 Jul 2015 12:12:08 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH v2 2/2] tracing: Fix for non-continuous cpu ids |
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On Tue, 9 Jun 2015 10:32:35 +0300 Gil Fruchter <gilf@ezchip.com> wrote:
> Currently exception occures due to access beyond buffer_iter > range while using index of cpu bigger than num_possible_cpus(). > Below there is an example for such exception when we use > cpus 0,1,16,17. > > In order to fix buffer allocation size for non-continuous cpu ids > we allocate according to the max cpu id and not according to the > amount of possible cpus. > > Example: > $ cat /sys/kernel/debug/tracing/per_cpu/cpu1/trace > Path: /bin/busybox > CPU: 0 PID: 82 Comm: cat Not tainted 4.0.0 #29 > task: 80734c80 ti: 80012000 task.ti: 80012000 > > [ECR ]: 0x00220100 => Invalid Read @ 0x00000000 by insn @ 0x800abafc > [EFA ]: 0x00000000 > [BLINK ]: ring_buffer_read_finish+0x24/0x64 > [ERET ]: rb_check_pages+0x20/0x188 > [STAT32]: 0x00001a00 : > BTA: 0x800abafc SP: 0x80013f0c FP: 0x57719cf8 > LPS: 0x200036b4 LPE: 0x200036b8 LPC: 0x00000000 > r00: 0x8002aca0 r01: 0x00001606 r02: 0x00000000 > r03: 0x00000001 r04: 0x00000000 r05: 0x804b4954 > r06: 0x00030003 r07: 0x8002a260 r08: 0x00000286 > r09: 0x00080002 r10: 0x00001006 r11: 0x807351a4 > r12: 0x00000001 > > Stack Trace: > rb_check_pages+0x20/0x188 > ring_buffer_read_finish+0x24/0x64 > tracing_release+0x4e/0x170 > __fput+0x62/0x158 > task_work_run+0xa2/0xd4 > do_notify_resume+0x52/0x7c > resume_user_mode_begin+0xdc/0xe0 > > Signed-off-by: Noam Camus <noamc@ezchip.com>
Why Noam's SoB tag? Did he author it?
-- Steve
> Signed-off-by: Gil Fruchter <gilf@ezchip.com> > --- > kernel/trace/trace.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 57ffc4a..8c5b382 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -3034,7 +3034,7 @@ __tracing_open(struct inode *inode, struct file *file, bool snapshot) > if (!iter) > return ERR_PTR(-ENOMEM); > > - iter->buffer_iter = kcalloc(num_possible_cpus(), sizeof(*iter->buffer_iter), > + iter->buffer_iter = kcalloc(nr_cpu_ids, sizeof(*iter->buffer_iter), > GFP_KERNEL); > if (!iter->buffer_iter) > goto release;
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