On Thu 03-08-23 22:46:11, Hugh Dickins wrote: > Commit "shmem: fix quota lock nesting in huge hole handling" was not so > good: Smatch caught shmem_recalc_inode()'s shmem_inode_unacct_blocks() > descending into quota_send_warning(): where blocking GFP_NOFS is used, > yet shmem_recalc_inode() is called holding the shmem inode's info->lock. > > Yes, both __dquot_alloc_space() and __dquot_free_space() are commented > "This operation can block, but only after everything is updated" - when > calling flush_warnings() at the end - both its print_warning() and its > quota_send_warning() may block. > > Rework shmem_recalc_inode() to take the shmem inode's info->lock inside, > and drop it before calling shmem_inode_unacct_blocks(). > > And why were the spin_locks disabling interrupts? That was just a relic > from when shmem_charge() and shmem_uncharge() were called while holding > i_pages xa_lock: stop disabling interrupts for info->lock now. > > To help stop me from making the same mistake again, add a might_sleep() > into shmem_inode_acct_block() and shmem_inode_unacct_blocks(); and those > functions have grown, so let the compiler decide whether to inline them. > > Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx> > Closes: https://lore.kernel.org/linux-fsdevel/ffd7ca34-7f2a-44ee-b05d-b54d920ce076@moroto.mountain/ > Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx> Thanks for the fix Hugh! The patch looks good to me so feel free to add: Reviewed-by: Jan Kara <jack@xxxxxxx> (FWIW for shmem code). Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
