Hi! > This may not risk an actual deadlock, since shmem inodes do not take > part in writeback accounting, but there are several easy ways to avoid > it.
...
> Take info->lock out of the chain and the possibility of deadlock or
> lockdep warning goes away.
It is unclear to me if actual possibility of deadlock exists or not,
but anyway:
> int retval = -ENOMEM;
>
> - spin_lock_irq(&info->lock);
> + /*
> + * What serializes the accesses to info->flags?
> + * ipc_lock_object() when called from shmctl_do_lock(),
> + * no serialization needed when called from shm_destroy().
> + */
> if (lock && !(info->flags & VM_LOCKED)) {
> if (!user_shm_lock(inode->i_size, user))
> goto out_nomem;
Should we have READ_ONCE() here? If it is okay, are concurency
sanitizers smart enough to realize that it is okay? Replacing warning
with different one would not be exactly a win...
Best regards,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures)
http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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