On Wed, 22 Aug 2007 10:08:09 +0800
Shaohua Li <[email protected]> wrote:
> commit dc386d4d1e98bb39fb967ee156cd456c802fc692 adds rcu_read_lock, but
> some routines in the lock range might sleep (like lock_buffer,
> aops->writepage), I saw a 'sleep in atomic' warning. It appears the
> patch has several versions before. Doing rcu_read_lock in PageAnon
> sounds break the case of PageAnon(page) && PageSwapCache(page),
> as .writepage might be called. The dummy anon patch maybe is ok.
>
Thank you for catching.
Maybe you're correct.
BTW, in PageAnon(page) && PageSwapCache(page) case, I can't find when
.writepage is called. Could you explain ?
In my understanding,
rcu_read_lock()
-> try_to_unmap()
-> move_to_new_page()
-> migrate_page() // swap has .migratepage member.
-> migrate_page_move_mapping().
-> migrate_page_copy().
-> remove_migration_ptes().
At quick glance, above path has no writepage() ops.
just replace swap's radix tree entry.
Thanks,
-Kame
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