Messages in this thread | | | Date | Thu, 15 Aug 2019 09:12:11 -0700 | From | Tejun Heo <> | Subject | Re: [PATCH 3/4] writeback, memcg: Implement cgroup_writeback_by_id() |
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On Thu, Aug 15, 2019 at 04:54:21PM +0200, Jan Kara wrote: > > + /* and find the associated wb */ > > + wb = wb_get_create(bdi, memcg_css, GFP_NOWAIT | __GFP_NOWARN); > > + if (!wb) { > > + ret = -ENOMEM; > > + goto out_css_put; > > + } > > One more thought: You don't want the "_create" part here, do you? If > there's any point in writing back using this wb, it must be attached to > some inode and thus it must exist. In the normal case wb_get_create() will > just fetch the reference and be done with it but when you feed garbage into > this function due to id going stale or frn structures getting corrupted due > to concurrent access, you can be creating bogus wb structures in bdi...
Yeah, it can create wbs unnecessarily which isn't critical but also is easy to fix. Will update.
Thanks.
-- tejun
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