Re: [PATCH 0/2] tracefs: inode alloc/free related fixes

On Wed,  7 Aug 2024 13:51:37 +0200
Mathias Krause [off-list ref] wrote:

Hi Steven,

We ran into yet another tracefs related bug but, fortunately, were able
to root cause it ourselves.

The problem only occurs when CONFIG_RANDSTRUCT is enabled and one gets
(un)lucky to hit a random seed that'll overlay the 'rcu' member of the
union with a list_head in 'vfs_inode' -- quite unlikely but, apparently,
we're exceptional "lucky" with our testing ;)

The first patch is more of an API correctness fix, to bring the tracefs
inode cache in line with all the other filesystems. The second patch
actually fixes the bug, which, I think, may also be the cause for what
Ilkka is seeing[1].

Ah, that would explain it, and why I never triggered it.

Please apply!

I have an update though.

-- Steve

Thanks,
Mathias

[1] https://lore.kernel.org/all/CAE4VaREzY+a2PvQJYJbfh8DwB4OP7kucZG-e28H22xyWob1w_A@mail.gmail.com/ (local)

Mathias Krause (2):
  tracefs: Fix inode allocation
  tracefs: Don't overlay 'struct inode'

 fs/tracefs/inode.c    | 2 +-
 fs/tracefs/internal.h | 6 ++----
 2 files changed, 3 insertions(+), 5 deletions(-)