On Thu, Jul 25, 2019 at 06:33:58PM +0900, Damien Le Moal wrote:
> + gfp_t gfp_mask;
> +
> switch (ext4_inode_journal_mode(inode)) {
> case EXT4_INODE_ORDERED_DATA_MODE:
> case EXT4_INODE_WRITEBACK_DATA_MODE:
> @@ -4019,6 +4019,14 @@ void ext4_set_aops(struct inode *inode)
> inode->i_mapping->a_ops = &ext4_da_aops;
> else
> inode->i_mapping->a_ops = &ext4_aops;
> +
> + /*
> + * Ensure all page cache allocations are done from GFP_NOFS context to
> + * prevent direct reclaim recursion back into the filesystem and blowing
> + * stacks or deadlocking.
> + */
> + gfp_mask = mapping_gfp_mask(inode->i_mapping);
> + mapping_set_gfp_mask(inode->i_mapping, (gfp_mask & ~(__GFP_FS)));
This looks like something that could hit every file systems, so
shouldn't we fix this in common code? We could also look into
just using memalloc_nofs_save for the page cache allocation path
instead of the per-mapping gfp_mask.
> }
>
> static int __ext4_block_zero_page_range(handle_t *handle,
> --
> 2.21.0
>
---end quoted text---
