From: Jan Kardell <jan.kardell@telliq.com>
To: Linux ARM <linux-arm-kernel@lists.infradead.org>
Cc: linux-kernel@vger.kernel.org,
Russell King <linux@armlinux.org.uk>,
linux-omap@vger.kernel.org, Tony Lindgren <tony@atomide.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org
Subject: arm: lockdep complaining about locks allocations in static memory
Date: Wed, 10 Mar 2021 14:54:30 +0100 [thread overview]
Message-ID: <6df24716-8b41-8e9a-f2f4-a0f5d49643bd@telliq.com> (raw)
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
next reply other threads:[~2021-03-10 13:55 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-10 13:54 Jan Kardell [this message]
2021-03-10 14:59 ` arm: lockdep complaining about locks allocations in static memory Russell King - ARM Linux admin
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