Re: [PATCH] mm: document risk of PF_MEMALLOC_NORECLAIM

[Michal Hocko <mhocko@suse.com>]

On Fri 16-08-24 07:26:06, Christoph Hellwig wrote:
> On Fri, Aug 16, 2024 at 10:54:37AM +0200, Michal Hocko wrote:
> > Yes, I think we should kill it before it spreads even more but I would
> > not like to make the existing user just broken. I have zero visibility
> > and understanding of the bcachefs code but from a quick look at __bch2_new_inode
> > it shouldn't be really terribly hard to push GFP_NOWAIT flag there
> > directly. It would require inode_init_always_gfp variant as well (to not
> > touch all existing callers that do not have any locking requirements but
> > I do not see any other nested allocations.
> 
> I'll probably have to go down into security_inode_alloc as well.

yes, I have done that as well. I was not sure about
inode_alloc_security. It has alloc in the name but none of the caller
actually allocate from there. lsm_inode_alloc was trivial to update.

> That being said there is no explanation for the behavior here in the
> commit logs or the code itself, so who knows.

-- 
Michal Hocko
SUSE Labs