Commit 786b3112 authored by Hugh Dickins's avatar Hugh Dickins Committed by Linus Torvalds
Browse files

mm: remove nrexceptional from inode: remove BUG_ON 

clear_inode()'s BUG_ON(!mapping_empty(&inode->i_data)) is unsafe: we
know of two ways in which nodes can and do (on rare occasions) get left
behind.  Until those are fixed, do not BUG_ON() nor even WARN_ON().

Yes, this will then leak those nodes (or the next user of the struct
inode may use them); but this has been happening for years, and the new
BUG_ON(!mapping_empty) was only guilty of revealing that.  A proper fix
will follow, but no hurry.

Link: https://lkml.kernel.org/r/alpine.LSU.2.11.2104292229380.16080@eggly.anvils


Signed-off-by: default avatarHugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8bc3c481

fs/inode.c

+8 −1
Original line number Diff line number Diff line
@@ -529,7 +529,14 @@ void clear_inode(struct inode *inode) 
	 */

	xa_lock_irq(&inode->i_data.i_pages);

	BUG_ON(inode->i_data.nrpages);

	BUG_ON(!mapping_empty(&inode->i_data));

	/*

	 * Almost always, mapping_empty(&inode->i_data) here; but there are

	 * two known and long-standing ways in which nodes may get left behind

	 * (when deep radix-tree node allocation failed partway; or when THP

	 * collapse_file() failed). Until those two known cases are cleaned up,

	 * or a cleanup function is called here, do not BUG_ON(!mapping_empty),

	 * nor even WARN_ON(!mapping_empty).

	 */

	xa_unlock_irq(&inode->i_data.i_pages);

	BUG_ON(!list_empty(&inode->i_data.private_list));

	BUG_ON(!(inode->i_state & I_FREEING));