[lkml]   [2006]   [Oct]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [patch 2/3] mm: fault vs invalidate/truncate race fix
Andrew Morton wrote:

>On Sat, 7 Oct 2006 15:06:21 +0200 (CEST)
>Nick Piggin <> wrote:
>>Fix the race between invalidate_inode_pages and do_no_page.
>- In do_no_page() there's a `goto retry' where we appear to have
> forgotten to (conditionally) unlock the page.

Hmm, the retry should be gone - it was only there for the
seqlock-ish truncate race code.

>- In do_no_page() the COW-break code seem to have forgotten to
> (conditionally) unlock the page which it just COWed?

It keeps the 'nopage_page' around and unlocks it at the end.
Last time I looked, this is required because truncate wants to
unmap 'even_cows', so we must hold the pagecache page locked
while instantiating the mapping on the cow page.

>- In do_no_page(), the unlock_page() which _is_ there doesn't test
> VM_CAN_INVALIDATE before deciding to unlock the page.

It does a conditional lock if !VM_CAN_INVALIDATE based on a
suggestion from Hugh. I don't disagree with that, but it can
go away in the next patch as we won't be calling into
->page_mkwrite (if that callback can be implemented with ->fault).


Send instant messages to your online friends

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2006-10-08 04:07    [W:0.056 / U:2.356 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site