Re: [RFC PATCH 1/2] mm/damon/reclaim: handle ctx allocation failure

[SeongJae Park <sj@kernel.org>]

On Thu, 28 May 2026 06:50:53 +0000 sashiko-bot@kernel.org wrote:

> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [High] The patch prevents loading the damon_reclaim module with the 'enabled=Y' parameter by returning -ENOMEM during parameter parsing.
> --
> 
> commit d55c0d692febe0a6f116ac49f1c1187ff2f47d7b
> Author: SeongJae Park <sj@kernel.org>
> mm/damon/reclaim: handle ctx allocation failure
> 
> This commit adds a check in damon_reclaim_enabled_store() to return -ENOMEM
> if the ctx pointer is NULL. This is intended to prevent a NULL pointer
> dereference if the context allocation failed during initialization.
> 
> Cc: stable@vger.kernel.org # 6.18.x
> 
> > diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
> > index ed446d00ef1cf..ce4499cf4b8b0 100644
> > --- a/mm/damon/reclaim.c
> > +++ b/mm/damon/reclaim.c
> > @@ -399,6 +399,10 @@ static int damon_reclaim_enabled_store(const char *val,
> >  	if (!damon_initialized())
> >  		return 0;
> >  
> > +	/* damon_modules_new_paddr_ctx_target() in the init function failed. */
> > +	if (!ctx)
> > +		return -ENOMEM;
> > +
> 
> [Severity: High]
> When the damon_reclaim module is loaded with the enabled=Y parameter,
> load_module() calls parse_args() before running the module's
> damon_reclaim_init() function. At this point, damon_initialized()
> returns true since the damon core is already initialized, but ctx is
> still NULL.
> 
> Will this new check return -ENOMEM and abort the entire module loading
> process during parameter parsing instead of successfully loading?

DAMON_RECLAIM is not a loadable but static module.  So this cannot happen.


Thanks,
SJ

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