Messages in this thread | | | From | Jan Kardell <> | Subject | arm: lockdep complaining about locks allocations in static memory | Date | Wed, 10 Mar 2021 14:54:30 +0100 |
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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.
//Jan
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