[PATCH 1/1] process_madvise.2: Add process_madvise man page
Michael Kerrisk (man-pages)
mtk.manpages at gmail.com
Thu Jan 28 20:31:19 UTC 2021
On 1/28/21 7:40 PM, Suren Baghdasaryan wrote:
> On Thu, Jan 28, 2021 at 4:24 AM Michael Kerrisk (man-pages)
> <mtk.manpages at gmail.com> wrote:
>> Hello Suren,
>> Thank you for writing this page! Some comments below.
> Thanks for the review!
> Couple questions below and I'll respin the new version once they are clarified.
Okay. See below.
>> On Wed, 20 Jan 2021 at 21:36, Suren Baghdasaryan <surenb at google.com> wrote:
Thanks for all the acks. That let's me know that you saw what I said.
>>> RETURN VALUE
>>> On success, process_madvise() returns the number of bytes advised. This
>>> return value may be less than the total number of requested bytes, if an
>>> error occurred. The caller should check return value to determine whether
>>> a partial advice occurred.
>> So there are three return values possible,
> Ok, I think I see your point. How about this instead:
Well, I'm glad you saw it, because I forgot to finish it. But yes,
you understood what I forgot to say.
> RETURN VALUE
> On success, process_madvise() returns the number of bytes advised. This
> return value may be less than the total number of requested bytes, if an
> error occurred after some iovec elements were already processed. The caller
> should check the return value to determine whether a partial
> advice occurred.
> On error, -1 is returned and errno is set appropriately.
We recently standardized some wording here:
s/appropriately/to indicate the error/.
>>> +The pointer
>>> +.I iovec
>>> +points to an array of iovec structures, defined in
>> "iovec" should be formatted as
>> .I iovec
> I think it is formatted that way above. What am I missing?
But also in "an array of iovec structures"...
> BTW, where should I be using .I vs .IR? I was looking for an answer
> but could not find it.
.B / .I == bold/italic this line
.BR / .IR == alternate bold/italic with normal (Roman) font.
.I iovec , # so that comma is not italic
.BR process_madvise ()
>>> +.I iovec
>>> +if one of its elements points to an invalid memory
>>> +region in the remote process. No further elements will be
>>> +processed beyond that point.
>>> +Permission to provide a hint to external process is governed by a
>>> +ptrace access mode
>>> +.B PTRACE_MODE_READ_REALCREDS
>>> +check; see
>>> +.BR ptrace (2)
>>> +.B CAP_SYS_ADMIN
>>> +capability that caller should have in order to affect performance
>>> +of an external process.
>> The preceding sentence is garbled. Missing words?
> Maybe I worded it incorrectly. What I need to say here is that the
> caller should have both PTRACE_MODE_READ_REALCREDS credentials and
> CAP_SYS_ADMIN capability. The first part I shamelessly copy/pasted
> from https://man7.org/linux/man-pages/man2/process_vm_readv.2.html and
> tried adding the second one to it, obviously unsuccessfully. Any
> advice on how to fix that?
I think you already got pretty close. How about:
Permission to provide a hint to another process is governed by a
ptrace access mode
BR ptrace (2));
in addition, the caller must have the
>>> +.B ESRCH
>>> +No process with ID
>>> +.I pidfd
>> Should this maybe be:
>> The target process does not exist (i.e., it has terminated and
>> been waited on).
>> See pidfd_send_signal(2).
> I "borrowed" mine from
> https://man7.org/linux/man-pages/man2/process_vm_readv.2.html but
> either one sounds good to me. Maybe for pidfd_send_signal the wording
> about termination is more important. Anyway, it's up to you. Just let
> me know which one to use.
I think the pidfd_send_signal(2) wording fits better.
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