Messages in this thread |  | | Date | Tue, 13 May 2003 18:16:16 -0500 | From | Dave McCracken <> | Subject | Re: Race between vmtruncate and mapped areas? |
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--On Tuesday, May 13, 2003 16:11:39 -0700 William Lee Irwin III <wli@holomorphy.com> wrote:
> Okay, what's stopping filemap_nopage() from fetching the page from > pagecache after one of the mm->mmap_sem's is dropped but before > truncate_inode_pages() removes the page? The fault path is only locked > out for one mm during one part of the operation. I can see taking > ->i_sem in do_no_page() fixing it, but not ->mmap_sem in vmtruncate() > (but of course that's _far_ too heavy-handed to merge at all).
mmap_sem is held for read across the entire fault, so by the time vmtruncate_list() can call zap_page_range() the page has been instantiated in the page table and will get removed.
Dave
====================================================================== Dave McCracken IBM Linux Base Kernel Team 1-512-838-3059 dmccr@us.ibm.com T/L 678-3059
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