lkml.org 
[lkml]   [2000]   [Oct]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: 2.4.0-test10-pre3:Oops in mm/filemap.c:filemap_write_pa
From
>>>>> " " == Linus Torvalds <torvalds@transmeta.com> writes:

> which is really really bad, because now you have the case that
> you have 'n' copies of the same page in memory, with 'n' users,
> out of which 'n-1' users have the wrong page. And those 'n-1'
> users don't even have any way of _knowing_ that they have the
> wrong page.

> Which is why we MUST NOT drop a page that has users. Really.

> I'm telling you that cases #4 and #5 are _much_ worse than your
> "solution" to case #2. And you argue that your solution is good
> only because you're completely ignoring cases #4 and #5.

No. I'm arguing (at 4:40am and while trying to keep one eye on our
detector's data acquisition) on the basis that whoever holds the file
lock has to have a guarantee of obtaining 100% accuracy on the locked
region.

I agree that dropping pages is ugly and that it will always give
problems with shared mmap(), so if it can be shown that clearing
PG_uptodate and rereading the same page will give the required
guarantee on locking, then I'm not going to complain.

Cheers,
Trond
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 12:41    [from the cache]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and my Meterkast|Read the blog