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Peter Zijlstra wrote: > On Thu, 2007-01-25 at 00:43 +1100, Nick Piggin wrote: > > >>>Have you seen the new launder_page() a_op? called from >>>invalidate_inode_pages2_range() >> >>It would have been nice to make that one into a more potentially >>useful generic callback. > > > That can still be done when the need arises, right? Yeah I guess so. >>But why was it introduced, exactly? I can't tell from the code or >>the discussion why NFS couldn't start the IO, and signal the caller >>to wait_on_page_writeback and retry? That seemed to me like the >>convetional fix. > > > to quote a bit: > > On Tue, 19 Dec 2006 18:19:38 -0500 > Trond Myklebust <trond.myklebust@fys.uio.no> wrote: > > >> NFS: Fix race in nfs_release_page() >> >> invalidate_inode_pages2() may set the dirty bit on a page owing to the call >> to unmap_mapping_range() after the page was locked. In order to fix this, >> NFS has hooked the releasepage() method. This, however leads to deadlocks >> in other parts of the VM. > > > and: > > >>>Now, arguably the VM shouldn't be calling try_to_release_page() with >>>__GFP_FS when it's holding a lock on a page. >>> >>>But otoh, NFS should never be running lock_page() within nfs_release_page() >>>against the page which was passed into nfs_release_page(). It'll deadlock >>>for sure. >> >>The reason why it is happening is that the last dirty page from that >>inode gets cleaned, resulting in a call to dput(). OK but what's the problem with just failing to release the page if it is dirty, I wonder? In the worst case, page reclaim will just end up doing a writeout to clean it. -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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