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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Nov 05, 2021 at 03:21:00PM +0100, Ard Biesheuvel wrote: > On Tue, 26 Oct 2021 at 15:13, Ard Biesheuvel wrote: > > > > The kmap_local conversion broke the ARM architecture, because the new > > code assumes that all PTEs used for creating kmaps form a linear array > > in memory, and uses array indexing to look up the kmap PTE belonging to > > a certain kmap index. > > > > On ARM, this cannot work, not only because the PTE pages may be > > non-adjacent in memory, but also because ARM/!LPAE interleaves hardware > > entries and extended entries (carrying software-only bits) in a way that > > is not compatible with array indexing. > > > > Fortunately, this only seems to affect configurations with more than 8 > > CPUs, due to the way the per-CPU kmap slots are organized in memory. > > > > Work around this by permitting an architecture to set a Kconfig symbol > > that signifies that the kmap PTEs do not form a lineary array in memory, > > and so the only way to locate the appropriate one is to walk the page > > tables. > > > > Reported-by: Quanyang Wang > > Signed-off-by: Ard Biesheuvel > > --- > > Ping? Can we get this fixed please? Who are you expecting to apply it? It seems to be touching only core code, so I don't think it's up to me - not without some kind of review from mm guys. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last! _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel