Messages in this thread | | | Date | Sat, 21 Jul 2012 11:57:41 -0500 | From | Jonathan Nieder <> | Subject | Re: [PATCH 17/17] NFS: nfs_migrate_page() does not wait for FS-Cache to finish with a page |
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Hi,
In February, David Howells wrote:
> nfs_migrate_page() does not wait for FS-Cache to finish with a page, probably > leading to the following bad-page-state: [...] > nfs_migrate_page() calls nfs_fscache_release_page() which doesn't actually wait > - even if __GFP_WAIT is set. The reason that doesn't wait is that > fscache_maybe_release_page() might deadlock the allocator as the work threads > writing to the cache may all end up sleeping on memory allocation. [...] > (1) Make nfs_migrate_page() wait. > > (2) Make fscache_maybe_release_page() honour the __GFP_WAIT flag. > > (3) Set a timeout around the wait. > > (4) Make nfs_migrate_page() return an error if the page is still busy. > > For the moment, I'll select (2) and (4). [...] > --- a/fs/nfs/write.c > +++ b/fs/nfs/write.c > @@ -1701,7 +1701,9 @@ int nfs_migrate_page(struct address_space *mapping, struct page *newpage, > if (PagePrivate(page)) > return -EBUSY; > > - nfs_fscache_release_page(page, GFP_KERNEL); > + ret = -EBUSY; > + if (!nfs_fscache_release_page(page, GFP_KERNEL)) > + goto out; > > return migrate_page(mapping, newpage, page, mode); > }
Small thing, but it looks like this was forward-ported incorrectly. Was this ever tested with CONFIG_MIGRATION enabled?
Hope that helps, Jonathan
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