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Message-Id: <20220127005447.143a840e9b0f67d894b8c54a@kernel.org> Date: Thu, 27 Jan 2022 00:54:47 +0900 From: Masami Hiramatsu <mhiramat@...nel.org> To: Jeff Xie <xiehuan09@...il.com> Cc: Steven Rostedt <rostedt@...dmis.org>, mingo@...hat.com, Tom Zanussi <zanussi@...nel.org>, linux-kernel@...r.kernel.org Subject: Re: [PATCH v7 0/4] trace: Introduce objtrace trigger to trace the kernel object Hi Jeff, On Wed, 19 Jan 2022 10:32:49 +0800 Jeff Xie <xiehuan09@...il.com> wrote: > > > Note: when change to use the ftrace_test_recursion_trylock, all the functions > > > will call the copy_from_kernel_nofault, I don't know where this is the problem now, > > > maybe should fall back to the usage in v6. > > > > > > for example: > > > > > > cat-118 [000] ...1. 1.458998: __bio_add_page <-bio_add_page object:0xffff88811a12e9e8 value:0x0 > > > cat-118 [000] ...2. 1.458998: copy_from_kernel_nofault <-trace_object_events_call object:0xffff88811a12e9e8 value:0x1000 > > > cat-118 [000] ...2. 1.458998: copy_from_kernel_nofault_allowed <-copy_from_kernel_nofault object:0xffff88811a12e9e8 value:0x1000 > > > cat-118 [000] ...1. 1.458998: __rcu_read_lock <-xa_load object:0xffff88811a12e9e8 value:0x1000 > > > cat-118 [000] ...2. 1.458998: copy_from_kernel_nofault <-trace_object_events_call object:0xffff88811a12e9e8 value:0x1000 > > > cat-118 [000] ...2. 1.458998: copy_from_kernel_nofault_allowed <-copy_from_kernel_nofault object:0xffff88811a12e9e8 value:0x1000 > > > cat-118 [000] ...1. 1.458998: __rcu_read_unlock <-xa_load object:0xffff88811a12e9e8 value:0x1000 > > > cat-118 [000] ...3. 1.458998: copy_from_kernel_nofault <-trace_object_events_call object:0xffff88811a12e9e8 value:0x1000 > > > cat-118 [000] ...3. 1.458998: copy_from_kernel_nofault_allowed <-copy_from_kernel_nofault object:0xffff88811a12e9e8 value:0x1000 > > > .... > > > > Hmm, this is strange, but I got it is the expected behavior, since the > > ftrace_test_recursion_trylock() accepts one stage recursion for the > > first event in the interrupt as transition event. I think you should revert that change and back to your own per-cpu recursion flag instead of using ftrace_test_recursion_trylock(). Thank you, -- Masami Hiramatsu <mhiramat@...nel.org>
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