[lvm-devel] Why print_log() is doing the memlock check?

[Alasdair G Kergon]

On Fri, Dec 15, 2006 at 06:32:00PM +0900, Shinn'ya Hoshino wrote:
> I am testing a writing error message to the /var/log/messages.
> However, a part of the error message wasn't written.
> It's blocked by memlock() function in print_log() function in lib/log.c.
 
LVM2 metadata changes go:
  suspend i/o to  device
  flip to new metadata
  resume i/o

While i/o is suspended you could have a situation where
most of the rest of the system blocks up until i/o is
resumed, so it is vital that the process that is going
to perform the resume does not itself also block up.
Writing a log message can lead to that, so logging
is disabled in such critical sections.

Override for testing with log/activation set to 1 in the config.

Alasdair
-- 
agk at redhat.com