linux-kernel - Re: [PATCH 4.14 023/159] mm/sparsemem: Allocate mem_section at runtime for CONFIG_SPARSEMEM

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Message-ID: <20171222151210.GB6874@kroah.com>
Date:   Fri, 22 Dec 2017 16:12:10 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Naresh Kamboju <naresh.kamboju@...aro.org>
Cc:     linux-kernel@...r.kernel.org,
        linux- stable <stable@...r.kernel.org>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Lutomirski <luto@...capital.net>,
        Borislav Petkov <bp@...e.de>,
        Cyrill Gorcunov <gorcunov@...nvz.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>, linux-mm@...ck.org,
        Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH 4.14 023/159] mm/sparsemem: Allocate mem_section at
 runtime for CONFIG_SPARSEMEM_EXTREME=y

On Fri, Dec 22, 2017 at 08:22:09PM +0530, Naresh Kamboju wrote:
> On 22 December 2017 at 19:48, Dan Rue <dan.rue@...aro.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@...ux.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@...ux.intel.com>
> >> Cc: Andrew Morton <akpm@...ux-foundation.org>
> >> Cc: Andy Lutomirski <luto@...capital.net>
> >> Cc: Borislav Petkov <bp@...e.de>
> >> Cc: Cyrill Gorcunov <gorcunov@...nvz.org>
> >> Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> >> Cc: Peter Zijlstra <peterz@...radead.org>
> >> Cc: Thomas Gleixner <tglx@...utronix.de>
> >> Cc: linux-mm@...ck.org
> >> Link: http://lkml.kernel.org/r/20170929140821.37654-2-kirill.shutemov@linux.intel.com
> >> Signed-off-by: Ingo Molnar <mingo@...nel.org>
> >> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.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@...ux.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