On Wed, Mar 10, 2021 at 02:54:30PM +0100, Jan Kardell wrote: > Hi, > > During work lift the software and kernel versions on our custom TI am3352 > board I started to see lockdep warnings after enabling CONFIG_PREEMT. > Lockdep seems to think the memory that previously was initmem is static > memory. I'm using linux 5.4, as that is what is used in the next OpenWrt > version. > > [ 92.198989] WARNING: CPU: 0 PID: 2015 at kernel/locking/lockdep.c:1119 > alloc_netdev_mqs+0xb4/0x3b0 > > I guess CONFIG_PREEMT just changes the timing of allocations, and is > otherwise irrelevant. > > This was fixed for s390 in linux 5.2 commit > 7a5da02de8d6eafba99556f8c98e5313edebb449 by adding the function > arch_is_kernel_initmem_freed(). Later a very similar change was made for > powerpc, and a different solution for x86. I now believe that is needed for > arm as well. Though I don't know the inner workings of arm memory management > so I don't know if an identical solution to s390 will do for arm, but my > experiments suggests it works for am335x. The commit message for s390 says > "virt == phys", but that seems not to be the case for my arm system. I don't see any reason this couldn't be added to arm, but it needs someone to create and test a patch - which implies that they need to have a problem that needs to be solved. As you seem to be experiencing the problem, it seems you are well suited to this. Thanks. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
