Messages in this thread | | | Date | Wed, 18 Aug 2004 20:07:24 -0400 (EDT) | From | Rajesh Venkatasubramanian <> | Subject | Re: page fault fastpath patch v2: fix race conditions, stats for 8,32 and 512 cpu SMP |
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On Wed, 18 Aug 2004, William Lee Irwin III wrote:
> William Lee Irwin III wrote: > >> It also protects against vma tree modifications in mainline, but rmap.c > >> shouldn't need it for vmas anymore, as the vma is rooted to the spot by > >> mapping->i_shared_lock for file pages and anon_vma->lock for anonymous. > > On Wed, Aug 18, 2004 at 07:50:21PM -0400, Rajesh Venkatasubramanian wrote: > > If I am reading the code correctly, then without page_table_lock > > in page_referenced_one(), we can race with exit_mmap() and page > > table pages can be freed under us. > > exit_mmap() has removed the vma from ->i_mmap and ->mmap prior to > unmapping the pages, so this should be safe unless that operation > can be caught while it's in progress.
No. Unfortunately exit_mmap() removes vmas from ->i_mmap after removing page table pages. Maybe we can reverse this, though.
Rajesh
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