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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: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Hugh Dickins 2021-05-04 18:32:57 -07:00 committed by Linus Torvalds
parent 8bc3c481b3
commit 786b31121a
1 changed files with 8 additions and 1 deletions
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9
fs/inode.c
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@ -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));