On Fri 23-11-18 16:04:04, Andrew Morton wrote:
> On Wed,  7 Nov 2018 11:18:26 +0100 Michal Hocko <mho...@kernel.org> wrote:
> 
> > From: Michal Hocko <mho...@suse.com>
> > 
> > __dump_page prints the mapping pointer but that is quite unhelpful
> > for many reports because the pointer itself only helps to distinguish
> > anon/ksm mappings from other ones (because of lowest bits
> > set). Sometimes it would be much more helpful to know what kind of
> > mapping that is actually and if we know this is a file mapping then also
> > try to resolve the dentry name.
> > 
> > ...
> >
> > --- a/mm/debug.c
> > +++ b/mm/debug.c
> >
> > ...
> >
> > @@ -70,6 +71,18 @@ void __dump_page(struct page *page, const char *reason)
> >     if (PageCompound(page))
> >             pr_cont(" compound_mapcount: %d", compound_mapcount(page));
> >     pr_cont("\n");
> > +   if (PageAnon(page))
> > +           pr_emerg("anon ");
> > +   else if (PageKsm(page))
> > +           pr_emerg("ksm ");
> > +   else if (mapping) {
> > +           pr_emerg("%ps ", mapping->a_ops);
> > +           if (mapping->host->i_dentry.first) {
> > +                   struct dentry *dentry;
> > +                   dentry = container_of(mapping->host->i_dentry.first, 
> > struct dentry, d_u.d_alias);
> > +                   pr_emerg("name:\"%*s\" ", dentry->d_name.len, 
> > dentry->d_name.name);
> > +           }
> > +   }
> 
> There has to be a better way of printing the filename.  It is so often
> needed.
> 
> The (poorly named and gleefully undocumented)
> take_dentry_name_snapshot() looks promising.  However it's unclear that
> __dump_page() is always called from contexts where
> take_dentry_name_snapshot() and release_dentry_name_snapshot() can be
> safely called.  Probably it's OK, but how to guarantee it?

http://lkml.kernel.org/r/20181125080834.gb12...@dhcp22.suse.cz as
suggested by Tetsuo?
-- 
Michal Hocko
SUSE Labs

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