Re: [PATCH 4.14 023/159] mm/sparsemem: Allocate mem_section at runtime for CONFIG_SPARSEMEM_EXTREME=y

Greg Kroah-Hartman
2017-12-22T15:12:11Z

On Fri, Dec 22, 2017 at 08:22:09PM +0530, Naresh Kamboju wrote:
> On 22 December 2017 at 19:48, Dan Rue <dan.rue@linaro.org> wrote:
> > On Fri, Dec 22, 2017 at 09:45:08AM +0100, Greg Kroah-Hartman wrote:
> >> 4.14-stable review patch. If anyone has any objections, please let me know.
> >>
> >> ------------------
> >>
> >> From: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> >>
> >> commit 83e3c48729d9ebb7af5a31a504f3fd6aff0348c4 upstream.
> >>
> >> Size of the mem_section[] array depends on the size of the physical address space.
> >>
> >> In preparation for boot-time switching between paging modes on x86-64
> >> we need to make the allocation of mem_section[] dynamic, because otherwise
> >> we waste a lot of RAM: with CONFIG_NODE_SHIFT=10, mem_section[] size is 32kB
> >> for 4-level paging and 2MB for 5-level paging mode.
> >>
> >> The patch allocates the array on the first call to sparse_memory_present_with_active_regions().
> >>
> >> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> >> Cc: Andrew Morton <akpm@linux-foundation.org>
> >> Cc: Andy Lutomirski <luto@amacapital.net>
> >> Cc: Borislav Petkov <bp@suse.de>
> >> Cc: Cyrill Gorcunov <gorcunov@openvz.org>
> >> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> >> Cc: Peter Zijlstra <peterz@infradead.org>
> >> Cc: Thomas Gleixner <tglx@linutronix.de>
> >> Cc: linux-mm@kvack.org
> >> Link: http://lkml.kernel.org/r/20170929140821.37654-2-kirill.shutemov@linux.intel.com
> >> Signed-off-by: Ingo Molnar <mingo@kernel.org>
> >> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> >
> > This patch causes a boot failure on arm64.
> >
> > Please drop this patch, or pick up the fix in:
> >
> > commit 629a359bdb0e0652a8227b4ff3125431995fec6e
> > Author: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> > Date: Tue Nov 7 11:33:37 2017 +0300
> >
> > mm/sparsemem: Fix ARM64 boot crash when CONFIG_SPARSEMEM_EXTREME=y
> >
> > See https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1527427.html
>
> +1.
> Boot failed on arm64 without 629a359b
> mm/sparsemem: Fix ARM64 boot crash when CONFIG_SPARSEMEM_EXTREME=y
>
> Boot Error log:
> --------------------
> [ 0.000000] Unable to handle kernel NULL pointer dereference at
> virtual address 00000000
> [ 0.000000] Mem abort info:
> [ 0.000000] Exception class = DABT (current EL), IL = 32 bits
> [ 0.000000] SET = 0, FnV = 0
> [ 0.000000] EA = 0, S1PTW = 0
> [ 0.000000] Data abort info:
> [ 0.000000] ISV = 0, ISS = 0x00000004
> [ 0.000000] CM = 0, WnR = 0
> [ 0.000000] [0000000000000000] user address but active_mm is swapper
> [ 0.000000] Internal error: Oops: 96000004 [#1] PREEMPT SMP
> [ 0.000000] Modules linked in:
> [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.14.9-rc1 #1
> [ 0.000000] Hardware name: ARM Juno development board (r2) (DT)
> [ 0.000000] task: ffff0000091d9380 task.stack: ffff0000091c0000
> [ 0.000000] PC is at memory_present+0x64/0xf4
> [ 0.000000] LR is at memory_present+0x38/0xf4
> [ 0.000000] pc : [<ffff0000090a1f54>] lr : [<ffff0000090a1f28>]
> pstate: 800000c5
> [ 0.000000] sp : ffff0000091c3e80
>
> More information,
> https://pastebin.com/KambxUwb

-rc2 is out with the fix, hopefully that survives longer :)

thanks,

greg k-h