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    SubjectRe: [PATCH] kmsg: Use vmalloc instead of kmalloc when writing
    On Sat, Mar 31, 2012 at 01:43, Greg KH <gregkh@linuxfoundation.org> wrote:
    > On Sat, Mar 31, 2012 at 12:02:39AM +0200, Sasha Levin wrote:
    >> On Fri, Mar 30, 2012 at 11:17 PM, Greg KH <gregkh@linuxfoundation.org> wrote:
    >> > On Fri, Mar 30, 2012 at 09:05:52PM +0000, Arnd Bergmann wrote:
    >> >> On Friday 30 March 2012, Thomas Gleixner wrote:
    >> >> > I think so. This is an interface to inject stuff into dmesg. Limiting
    >> >> > that to a reasonable size makes sense. We can probably limit it to
    >> >> > something small like 1024, but I don't know about the "ideas" of those
    >> >> > folks who think that it's a great idea to do it at all.
    >> >>
    >> >> I guess a page would be a reasonable size, similar to what we do for
    >> >> sysfs.
    >> >
    >> > Ok. Sasha, as you seem to have noticed this, care to dig in syslog and
    >> > systemd to get an idea of the buffer sizes they are expecting to pass
    >> > into kmsg, and if they can handle a short write properly?  If so,
    >> > restricting it to a page is fine with me, otherwise we might want to
    >> > make it a bit bigger.
    >>
    >> systemd seems to use posix LINE_MAX sized buffers, syslog-ng uses
    >> dynamic strings, but it chews them one line at the time.
    >
    > Ok, care to update this patch with a max size?
    >
    > And again, does systemd and syslog-ng handle short writes properly?

    Printk has a static scratch buffer of 1024, we can not really process
    more than that, so we can limit the /dev/kmsg write() to the same
    size, I guess.

    Thanks,
    Kay
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