On Tue 26 Jan 10:21 CST 2021, Mark Rutland wrote: > On Tue, Jan 26, 2021 at 02:58:33PM +0000, Matthew Wilcox wrote: > > On Tue, Jan 26, 2021 at 10:47:34AM +0000, Mark Rutland wrote: > > > Hi, > > > > > > When fuzzing arm64 with Syzkaller, I'm seeing some splats where > > > this_cpu_ptr() is used in the bowels of idr_alloc(), by way of > > > radix_tree_node_alloc(), in a preemptible context: > > > > I sent a patch to fix this last June. The maintainer seems to be > > under the impression that I care an awful lot more about their > > code than I do. > > > > https://lore.kernel.org/netdev/20200605120037.17427-1-wi...@infradead.org/ > > Ah; I hadn't spotted the (glaringly obvious) GFP_ATOMIC abuse, thanks > for the pointer, and sorry for the noise. >
I'm afraid this isn't as obvious to me as it is to you. Are you saying that one must not use GFP_ATOMIC in non-atomic contexts? That said, glancing at the code I'm puzzled to why it would use GFP_ATOMIC. > It looks like Eric was after a fix that trivially backported to v4.7 > (and hence couldn't rely on xarray) but instead it just got left broken > for months. :/ > > Bjorn, is this something you care about? You seem to have the most > commits to the file, and otherwise the official maintainer is Dave > Miller per get_maintainer.pl. > I certainly care about qrtr working and remember glancing at Matthew's patch, but seems like I never found time to properly review it. > It is very tempting to make the config option depend on BROKEN... > I hear you and that would be bad, so I'll make sure to take a proper look at this and Matthew's patch. Thanks, Bjorn
