| Message ID | 1466738027-15066-2-git-send-email-dennis.chen@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 24 June 2016 at 05:13, Dennis Chen <dennis.chen@arm.com> wrote: > When booting an ACPI enabled kernel with 'mem=', probably the ACPI data > regions loaded by firmware will beyond the limit of the memory, in this > case we need to nomap the region above the limit while not removing > it from memblock, because once region removed from memblock, the ACPI > will think that region is not a normal memory and map it as device type > memory accordingly. Since the ACPI core will produce non-alignment access > when paring AML data stream, hence result in alignment fault upon the io > mapped memory space. > > For example, below is an alignment exception observed on softIron board > when booting the kernel with 'acpi=force mem=8G': > ... > [ 0.542475] Unable to handle kernel paging request at virtual address ffff0000080521e7 > [ 0.550457] pgd = ffff000008aa0000 > [ 0.553880] [ffff0000080521e7] *pgd=000000801fffe003, *pud=000000801fffd003, *pmd=000000801fffc003, *pte=00e80083ff1c1707 > [ 0.564939] Internal error: Oops: 96000021 [#1] PREEMPT SMP > [ 0.570553] Modules linked in: > [ 0.573626] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.7.0-rc3-next-20160616+ #172 > [ 0.581344] Hardware name: AMD Overdrive/Supercharger/Default string, BIOS ROD1001A 02/09/2016 > [ 0.590025] task: ffff800001ef0000 ti: ffff800001ef8000 task.ti: ffff800001ef8000 > [ 0.597571] PC is at acpi_ns_lookup+0x520/0x734 > [ 0.602134] LR is at acpi_ns_lookup+0x4a4/0x734 > [ 0.606693] pc : [<ffff0000083b8b10>] lr : [<ffff0000083b8a94>] pstate: 60000045 > [ 0.614145] sp : ffff800001efb8b0 > [ 0.617478] x29: ffff800001efb8c0 x28: 000000000000001b > [ 0.622829] x27: 0000000000000001 x26: 0000000000000000 > [ 0.628181] x25: ffff800001efb9e8 x24: ffff000008a10000 > [ 0.633531] x23: 0000000000000001 x22: 0000000000000001 > [ 0.638881] x21: ffff000008724000 x20: 000000000000001b > [ 0.644230] x19: ffff0000080521e7 x18: 000000000000000d > [ 0.649580] x17: 00000000000038ff x16: 0000000000000002 > [ 0.654929] x15: 0000000000000007 x14: 0000000000007fff > [ 0.660278] x13: ffffff0000000000 x12: 0000000000000018 > [ 0.665627] x11: 000000001fffd200 x10: 00000000ffffff76 > [ 0.670978] x9 : 000000000000005f x8 : ffff000008725fa8 > [ 0.676328] x7 : ffff000008a8df70 x6 : ffff000008a8df70 > [ 0.681679] x5 : ffff000008a8d000 x4 : 0000000000000010 > [ 0.687027] x3 : 0000000000000010 x2 : 000000000000000c > [ 0.692378] x1 : 0000000000000006 x0 : 0000000000000000 > ... > [ 1.262235] [<ffff0000083b8b10>] acpi_ns_lookup+0x520/0x734 > [ 1.267845] [<ffff0000083a7160>] acpi_ds_load1_begin_op+0x174/0x4fc > [ 1.274156] [<ffff0000083c1f4c>] acpi_ps_build_named_op+0xf8/0x220 > [ 1.280380] [<ffff0000083c227c>] acpi_ps_create_op+0x208/0x33c > [ 1.286254] [<ffff0000083c1820>] acpi_ps_parse_loop+0x204/0x838 > [ 1.292215] [<ffff0000083c2fd4>] acpi_ps_parse_aml+0x1bc/0x42c > [ 1.298090] [<ffff0000083bc6e8>] acpi_ns_one_complete_parse+0x1e8/0x22c > [ 1.304753] [<ffff0000083bc7b8>] acpi_ns_parse_table+0x8c/0x128 > [ 1.310716] [<ffff0000083bb8fc>] acpi_ns_load_table+0xc0/0x1e8 > [ 1.316591] [<ffff0000083c9068>] acpi_tb_load_namespace+0xf8/0x2e8 > [ 1.322818] [<ffff000008984128>] acpi_load_tables+0x7c/0x110 > [ 1.328516] [<ffff000008982ea4>] acpi_init+0x90/0x2c0 > [ 1.333603] [<ffff0000080819fc>] do_one_initcall+0x38/0x12c > [ 1.339215] [<ffff000008960cd4>] kernel_init_freeable+0x148/0x1ec > [ 1.345353] [<ffff0000086b7d30>] kernel_init+0x10/0xec > [ 1.350529] [<ffff000008084e10>] ret_from_fork+0x10/0x40 > [ 1.355878] Code: b9009fbc 2a00037b 36380057 3219037b (b9400260) > [ 1.362035] ---[ end trace 03381e5eb0a24de4 ]--- > [ 1.366691] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b > > With 'efi=debug', we can see those ACPI regions loaded by firmware on > that board as: > [ 0.000000] efi: 0x0083ff1b5000-0x0083ff1c2fff [ACPI Reclaim Memory| | | | | | | | |WB|WT|WC|UC]* > [ 0.000000] efi: 0x0083ff223000-0x0083ff224fff [ACPI Memory NVS | | | | | | | | |WB|WT|WC|UC]* > > This patch is trying to address the above issues by nomaping the region > instead of removing it. > > Signed-off-by: Dennis Chen <dennis.chen@arm.com> > Cc: Catalin Marinas <catalin.marinas@arm.com> > Cc: Steve Capper <steve.capper@arm.com> > Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> > Cc: Will Deacon <will.deacon@arm.com> > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > Cc: Matt Fleming <matt@codeblueprint.co.uk> > Cc: linux-mm@kvack.org > Cc: linux-acpi@vger.kernel.org > Cc: linux-efi@vger.kernel.org > --- > Changes in v2: > Update the commit message and remove the memblock_is_map_memory() check > according to the suggestion from Mark Rutland. > > arch/arm64/mm/init.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index d45f862..6af2456 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -222,12 +222,13 @@ void __init arm64_memblock_init(void) > > /* > * Apply the memory limit if it was set. Since the kernel may be loaded > - * high up in memory, add back the kernel region that must be accessible > - * via the linear mapping. > + * in the memory regions above the limit, so we need to clear the > + * MEMBLOCK_NOMAP flag of this region to make it can be accessible via > + * the linear mapping. > */ > if (memory_limit != (phys_addr_t)ULLONG_MAX) { > - memblock_enforce_memory_limit(memory_limit); > - memblock_add(__pa(_text), (u64)(_end - _text)); > + memblock_mem_limit_mark_nomap(memory_limit); > + memblock_clear_nomap(__pa(_text), (u64)(_end - _text)); Up until now, we have ignored the effect of having NOMAP memblocks on the return values of functions like memblock_phys_mem_size() and memblock_mem_size(), since they could reasonably be expected to cover only a small slice of all available memory. However, after applying this patch, it may well be the case that most of memory is marked NOMAP, and these functions will cease to work as expected. This means NOMAP is really only suited to punch some holes into the kernel direct mapping, and so implementing the memory limit by marking everything NOMAP is not the way to go. Instead, we should probably reorder the init sequence so that the regions that are reserved in the UEFI memory map are declared and marked NOMAP [again] after applying the memory limit in the old way.
On Fri, Jun 24, 2016 at 12:43:52PM +0200, Ard Biesheuvel wrote: > On 24 June 2016 at 05:13, Dennis Chen <dennis.chen@arm.com> wrote: > > When booting an ACPI enabled kernel with 'mem=', probably the ACPI data > > regions loaded by firmware will beyond the limit of the memory, in this > > case we need to nomap the region above the limit while not removing > > it from memblock, because once region removed from memblock, the ACPI > > will think that region is not a normal memory and map it as device type > > memory accordingly. Since the ACPI core will produce non-alignment access > > when paring AML data stream, hence result in alignment fault upon the io > > mapped memory space. > > > > For example, below is an alignment exception observed on softIron board > > when booting the kernel with 'acpi=force mem=8G': > > ... > > [ 0.542475] Unable to handle kernel paging request at virtual address ffff0000080521e7 > > [ 0.550457] pgd = ffff000008aa0000 > > [ 0.553880] [ffff0000080521e7] *pgd=000000801fffe003, *pud=000000801fffd003, *pmd=000000801fffc003, *pte=00e80083ff1c1707 > > [ 0.564939] Internal error: Oops: 96000021 [#1] PREEMPT SMP > > [ 0.570553] Modules linked in: > > [ 0.573626] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.7.0-rc3-next-20160616+ #172 > > [ 0.581344] Hardware name: AMD Overdrive/Supercharger/Default string, BIOS ROD1001A 02/09/2016 > > [ 0.590025] task: ffff800001ef0000 ti: ffff800001ef8000 task.ti: ffff800001ef8000 > > [ 0.597571] PC is at acpi_ns_lookup+0x520/0x734 > > [ 0.602134] LR is at acpi_ns_lookup+0x4a4/0x734 > > [ 0.606693] pc : [<ffff0000083b8b10>] lr : [<ffff0000083b8a94>] pstate: 60000045 > > [ 0.614145] sp : ffff800001efb8b0 > > [ 0.617478] x29: ffff800001efb8c0 x28: 000000000000001b > > [ 0.622829] x27: 0000000000000001 x26: 0000000000000000 > > [ 0.628181] x25: ffff800001efb9e8 x24: ffff000008a10000 > > [ 0.633531] x23: 0000000000000001 x22: 0000000000000001 > > [ 0.638881] x21: ffff000008724000 x20: 000000000000001b > > [ 0.644230] x19: ffff0000080521e7 x18: 000000000000000d > > [ 0.649580] x17: 00000000000038ff x16: 0000000000000002 > > [ 0.654929] x15: 0000000000000007 x14: 0000000000007fff > > [ 0.660278] x13: ffffff0000000000 x12: 0000000000000018 > > [ 0.665627] x11: 000000001fffd200 x10: 00000000ffffff76 > > [ 0.670978] x9 : 000000000000005f x8 : ffff000008725fa8 > > [ 0.676328] x7 : ffff000008a8df70 x6 : ffff000008a8df70 > > [ 0.681679] x5 : ffff000008a8d000 x4 : 0000000000000010 > > [ 0.687027] x3 : 0000000000000010 x2 : 000000000000000c > > [ 0.692378] x1 : 0000000000000006 x0 : 0000000000000000 > > ... > > [ 1.262235] [<ffff0000083b8b10>] acpi_ns_lookup+0x520/0x734 > > [ 1.267845] [<ffff0000083a7160>] acpi_ds_load1_begin_op+0x174/0x4fc > > [ 1.274156] [<ffff0000083c1f4c>] acpi_ps_build_named_op+0xf8/0x220 > > [ 1.280380] [<ffff0000083c227c>] acpi_ps_create_op+0x208/0x33c > > [ 1.286254] [<ffff0000083c1820>] acpi_ps_parse_loop+0x204/0x838 > > [ 1.292215] [<ffff0000083c2fd4>] acpi_ps_parse_aml+0x1bc/0x42c > > [ 1.298090] [<ffff0000083bc6e8>] acpi_ns_one_complete_parse+0x1e8/0x22c > > [ 1.304753] [<ffff0000083bc7b8>] acpi_ns_parse_table+0x8c/0x128 > > [ 1.310716] [<ffff0000083bb8fc>] acpi_ns_load_table+0xc0/0x1e8 > > [ 1.316591] [<ffff0000083c9068>] acpi_tb_load_namespace+0xf8/0x2e8 > > [ 1.322818] [<ffff000008984128>] acpi_load_tables+0x7c/0x110 > > [ 1.328516] [<ffff000008982ea4>] acpi_init+0x90/0x2c0 > > [ 1.333603] [<ffff0000080819fc>] do_one_initcall+0x38/0x12c > > [ 1.339215] [<ffff000008960cd4>] kernel_init_freeable+0x148/0x1ec > > [ 1.345353] [<ffff0000086b7d30>] kernel_init+0x10/0xec > > [ 1.350529] [<ffff000008084e10>] ret_from_fork+0x10/0x40 > > [ 1.355878] Code: b9009fbc 2a00037b 36380057 3219037b (b9400260) > > [ 1.362035] ---[ end trace 03381e5eb0a24de4 ]--- > > [ 1.366691] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b > > > > With 'efi=debug', we can see those ACPI regions loaded by firmware on > > that board as: > > [ 0.000000] efi: 0x0083ff1b5000-0x0083ff1c2fff [ACPI Reclaim Memory| | | | | | | | |WB|WT|WC|UC]* > > [ 0.000000] efi: 0x0083ff223000-0x0083ff224fff [ACPI Memory NVS | | | | | | | | |WB|WT|WC|UC]* > > > > This patch is trying to address the above issues by nomaping the region > > instead of removing it. > > > > Signed-off-by: Dennis Chen <dennis.chen@arm.com> > > Cc: Catalin Marinas <catalin.marinas@arm.com> > > Cc: Steve Capper <steve.capper@arm.com> > > Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> > > Cc: Will Deacon <will.deacon@arm.com> > > Cc: Mark Rutland <mark.rutland@arm.com> > > Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > > Cc: Matt Fleming <matt@codeblueprint.co.uk> > > Cc: linux-mm@kvack.org > > Cc: linux-acpi@vger.kernel.org > > Cc: linux-efi@vger.kernel.org > > --- > > Changes in v2: > > Update the commit message and remove the memblock_is_map_memory() check > > according to the suggestion from Mark Rutland. > > > > arch/arm64/mm/init.c | 9 +++++---- > > 1 file changed, 5 insertions(+), 4 deletions(-) > > > > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > > index d45f862..6af2456 100644 > > --- a/arch/arm64/mm/init.c > > +++ b/arch/arm64/mm/init.c > > @@ -222,12 +222,13 @@ void __init arm64_memblock_init(void) > > > > /* > > * Apply the memory limit if it was set. Since the kernel may be loaded > > - * high up in memory, add back the kernel region that must be accessible > > - * via the linear mapping. > > + * in the memory regions above the limit, so we need to clear the > > + * MEMBLOCK_NOMAP flag of this region to make it can be accessible via > > + * the linear mapping. > > */ > > if (memory_limit != (phys_addr_t)ULLONG_MAX) { > > - memblock_enforce_memory_limit(memory_limit); > > - memblock_add(__pa(_text), (u64)(_end - _text)); > > + memblock_mem_limit_mark_nomap(memory_limit); > > + memblock_clear_nomap(__pa(_text), (u64)(_end - _text)); > > Up until now, we have ignored the effect of having NOMAP memblocks on > the return values of functions like memblock_phys_mem_size() and > memblock_mem_size(), since they could reasonably be expected to cover > only a small slice of all available memory. However, after applying > this patch, it may well be the case that most of memory is marked > NOMAP, and these functions will cease to work as expected. > Hi Ard, I noticed these inconsistences as you mentioned, but seems the available memory is limited correctly. For this case('mem='), will it bring some substantive side effects except that some log messages maybe confusing? > > This means NOMAP is really only suited to punch some holes into the > kernel direct mapping, and so implementing the memory limit by marking > everything NOMAP is not the way to go. Instead, we should probably > reorder the init sequence so that the regions that are reserved in the > UEFI memory map are declared and marked NOMAP [again] after applying > the memory limit in the old way. > Before this patch, I have another one addressing the same issue [1], with that patch we'll not have these inconsistences, but it looks like a little bit complicated, so it becomes current one. Any comments about that? [1]http://lists.infradead.org/pipermail/linux-arm-kernel/2016-June/438443.html Thanks, Dennis > > -- > Ard. >
On 24 June 2016 at 14:01, Dennis Chen <dennis.chen@arm.com> wrote: > On Fri, Jun 24, 2016 at 12:43:52PM +0200, Ard Biesheuvel wrote: >> On 24 June 2016 at 05:13, Dennis Chen <dennis.chen@arm.com> wrote: >> > When booting an ACPI enabled kernel with 'mem=', probably the ACPI data >> > regions loaded by firmware will beyond the limit of the memory, in this >> > case we need to nomap the region above the limit while not removing >> > it from memblock, because once region removed from memblock, the ACPI >> > will think that region is not a normal memory and map it as device type >> > memory accordingly. Since the ACPI core will produce non-alignment access >> > when paring AML data stream, hence result in alignment fault upon the io >> > mapped memory space. >> > >> > For example, below is an alignment exception observed on softIron board >> > when booting the kernel with 'acpi=force mem=8G': >> > ... >> > [ 0.542475] Unable to handle kernel paging request at virtual address ffff0000080521e7 >> > [ 0.550457] pgd = ffff000008aa0000 >> > [ 0.553880] [ffff0000080521e7] *pgd=000000801fffe003, *pud=000000801fffd003, *pmd=000000801fffc003, *pte=00e80083ff1c1707 >> > [ 0.564939] Internal error: Oops: 96000021 [#1] PREEMPT SMP >> > [ 0.570553] Modules linked in: >> > [ 0.573626] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.7.0-rc3-next-20160616+ #172 >> > [ 0.581344] Hardware name: AMD Overdrive/Supercharger/Default string, BIOS ROD1001A 02/09/2016 >> > [ 0.590025] task: ffff800001ef0000 ti: ffff800001ef8000 task.ti: ffff800001ef8000 >> > [ 0.597571] PC is at acpi_ns_lookup+0x520/0x734 >> > [ 0.602134] LR is at acpi_ns_lookup+0x4a4/0x734 >> > [ 0.606693] pc : [<ffff0000083b8b10>] lr : [<ffff0000083b8a94>] pstate: 60000045 >> > [ 0.614145] sp : ffff800001efb8b0 >> > [ 0.617478] x29: ffff800001efb8c0 x28: 000000000000001b >> > [ 0.622829] x27: 0000000000000001 x26: 0000000000000000 >> > [ 0.628181] x25: ffff800001efb9e8 x24: ffff000008a10000 >> > [ 0.633531] x23: 0000000000000001 x22: 0000000000000001 >> > [ 0.638881] x21: ffff000008724000 x20: 000000000000001b >> > [ 0.644230] x19: ffff0000080521e7 x18: 000000000000000d >> > [ 0.649580] x17: 00000000000038ff x16: 0000000000000002 >> > [ 0.654929] x15: 0000000000000007 x14: 0000000000007fff >> > [ 0.660278] x13: ffffff0000000000 x12: 0000000000000018 >> > [ 0.665627] x11: 000000001fffd200 x10: 00000000ffffff76 >> > [ 0.670978] x9 : 000000000000005f x8 : ffff000008725fa8 >> > [ 0.676328] x7 : ffff000008a8df70 x6 : ffff000008a8df70 >> > [ 0.681679] x5 : ffff000008a8d000 x4 : 0000000000000010 >> > [ 0.687027] x3 : 0000000000000010 x2 : 000000000000000c >> > [ 0.692378] x1 : 0000000000000006 x0 : 0000000000000000 >> > ... >> > [ 1.262235] [<ffff0000083b8b10>] acpi_ns_lookup+0x520/0x734 >> > [ 1.267845] [<ffff0000083a7160>] acpi_ds_load1_begin_op+0x174/0x4fc >> > [ 1.274156] [<ffff0000083c1f4c>] acpi_ps_build_named_op+0xf8/0x220 >> > [ 1.280380] [<ffff0000083c227c>] acpi_ps_create_op+0x208/0x33c >> > [ 1.286254] [<ffff0000083c1820>] acpi_ps_parse_loop+0x204/0x838 >> > [ 1.292215] [<ffff0000083c2fd4>] acpi_ps_parse_aml+0x1bc/0x42c >> > [ 1.298090] [<ffff0000083bc6e8>] acpi_ns_one_complete_parse+0x1e8/0x22c >> > [ 1.304753] [<ffff0000083bc7b8>] acpi_ns_parse_table+0x8c/0x128 >> > [ 1.310716] [<ffff0000083bb8fc>] acpi_ns_load_table+0xc0/0x1e8 >> > [ 1.316591] [<ffff0000083c9068>] acpi_tb_load_namespace+0xf8/0x2e8 >> > [ 1.322818] [<ffff000008984128>] acpi_load_tables+0x7c/0x110 >> > [ 1.328516] [<ffff000008982ea4>] acpi_init+0x90/0x2c0 >> > [ 1.333603] [<ffff0000080819fc>] do_one_initcall+0x38/0x12c >> > [ 1.339215] [<ffff000008960cd4>] kernel_init_freeable+0x148/0x1ec >> > [ 1.345353] [<ffff0000086b7d30>] kernel_init+0x10/0xec >> > [ 1.350529] [<ffff000008084e10>] ret_from_fork+0x10/0x40 >> > [ 1.355878] Code: b9009fbc 2a00037b 36380057 3219037b (b9400260) >> > [ 1.362035] ---[ end trace 03381e5eb0a24de4 ]--- >> > [ 1.366691] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b >> > >> > With 'efi=debug', we can see those ACPI regions loaded by firmware on >> > that board as: >> > [ 0.000000] efi: 0x0083ff1b5000-0x0083ff1c2fff [ACPI Reclaim Memory| | | | | | | | |WB|WT|WC|UC]* >> > [ 0.000000] efi: 0x0083ff223000-0x0083ff224fff [ACPI Memory NVS | | | | | | | | |WB|WT|WC|UC]* >> > >> > This patch is trying to address the above issues by nomaping the region >> > instead of removing it. >> > >> > Signed-off-by: Dennis Chen <dennis.chen@arm.com> >> > Cc: Catalin Marinas <catalin.marinas@arm.com> >> > Cc: Steve Capper <steve.capper@arm.com> >> > Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> >> > Cc: Will Deacon <will.deacon@arm.com> >> > Cc: Mark Rutland <mark.rutland@arm.com> >> > Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> >> > Cc: Matt Fleming <matt@codeblueprint.co.uk> >> > Cc: linux-mm@kvack.org >> > Cc: linux-acpi@vger.kernel.org >> > Cc: linux-efi@vger.kernel.org >> > --- >> > Changes in v2: >> > Update the commit message and remove the memblock_is_map_memory() check >> > according to the suggestion from Mark Rutland. >> > >> > arch/arm64/mm/init.c | 9 +++++---- >> > 1 file changed, 5 insertions(+), 4 deletions(-) >> > >> > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c >> > index d45f862..6af2456 100644 >> > --- a/arch/arm64/mm/init.c >> > +++ b/arch/arm64/mm/init.c >> > @@ -222,12 +222,13 @@ void __init arm64_memblock_init(void) >> > >> > /* >> > * Apply the memory limit if it was set. Since the kernel may be loaded >> > - * high up in memory, add back the kernel region that must be accessible >> > - * via the linear mapping. >> > + * in the memory regions above the limit, so we need to clear the >> > + * MEMBLOCK_NOMAP flag of this region to make it can be accessible via >> > + * the linear mapping. >> > */ >> > if (memory_limit != (phys_addr_t)ULLONG_MAX) { >> > - memblock_enforce_memory_limit(memory_limit); >> > - memblock_add(__pa(_text), (u64)(_end - _text)); >> > + memblock_mem_limit_mark_nomap(memory_limit); >> > + memblock_clear_nomap(__pa(_text), (u64)(_end - _text)); >> >> Up until now, we have ignored the effect of having NOMAP memblocks on >> the return values of functions like memblock_phys_mem_size() and >> memblock_mem_size(), since they could reasonably be expected to cover >> only a small slice of all available memory. However, after applying >> this patch, it may well be the case that most of memory is marked >> NOMAP, and these functions will cease to work as expected. >> > Hi Ard, I noticed these inconsistences as you mentioned, but seems the > available memory is limited correctly. For this case('mem='), will it bring > some substantive side effects except that some log messages maybe confusing? That is exactly the question that needs answering before we can merge these patches. I know we consider mem= a development hack, but the intent is to make it appear to the kernel as if only a smaller amount of memory is available to the kernel, and this is signficantly different from having memblock_mem_size() et al return much larger values than what is actually available. Perhaps this doesn't matter at all, but it is something we must discuss before proceeding with these changes. >> >> This means NOMAP is really only suited to punch some holes into the >> kernel direct mapping, and so implementing the memory limit by marking >> everything NOMAP is not the way to go. Instead, we should probably >> reorder the init sequence so that the regions that are reserved in the >> UEFI memory map are declared and marked NOMAP [again] after applying >> the memory limit in the old way. >> > Before this patch, I have another one addressing the same issue [1], with > that patch we'll not have these inconsistences, but it looks like a little > bit complicated, so it becomes current one. Any comments about that? > > [1]http://lists.infradead.org/pipermail/linux-arm-kernel/2016-June/438443.html > The problem caused by mem= is that it removes regions that are marked NOMAP. So instead of marking everything above the limit NOMAP, I would much rather see an alternative implementation of memblock_enforce_memory_limit() that enforces the mem= limit by only removing memblocks that have to NOMAP flag cleared, and leaving the NOMAP ones where they are.
On Fri, Jun 24, 2016 at 04:12:02PM +0200, Ard Biesheuvel wrote: > On 24 June 2016 at 14:01, Dennis Chen <dennis.chen@arm.com> wrote: > > On Fri, Jun 24, 2016 at 12:43:52PM +0200, Ard Biesheuvel wrote: > >> On 24 June 2016 at 05:13, Dennis Chen <dennis.chen@arm.com> wrote: > >> > When booting an ACPI enabled kernel with 'mem=', probably the ACPI data > >> > regions loaded by firmware will beyond the limit of the memory, in this > >> > case we need to nomap the region above the limit while not removing > >> > it from memblock, because once region removed from memblock, the ACPI > >> > will think that region is not a normal memory and map it as device type > >> > memory accordingly. Since the ACPI core will produce non-alignment access > >> > when paring AML data stream, hence result in alignment fault upon the io > >> > mapped memory space. > >> > > >> > For example, below is an alignment exception observed on softIron board > >> > when booting the kernel with 'acpi=force mem=8G': > >> > ... > >> > [ 0.542475] Unable to handle kernel paging request at virtual address ffff0000080521e7 > >> > [ 0.550457] pgd = ffff000008aa0000 > >> > [ 0.553880] [ffff0000080521e7] *pgd=000000801fffe003, *pud=000000801fffd003, *pmd=000000801fffc003, *pte=00e80083ff1c1707 > >> > [ 0.564939] Internal error: Oops: 96000021 [#1] PREEMPT SMP > >> > [ 0.570553] Modules linked in: > >> > [ 0.573626] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.7.0-rc3-next-20160616+ #172 > >> > [ 0.581344] Hardware name: AMD Overdrive/Supercharger/Default string, BIOS ROD1001A 02/09/2016 > >> > [ 0.590025] task: ffff800001ef0000 ti: ffff800001ef8000 task.ti: ffff800001ef8000 > >> > [ 0.597571] PC is at acpi_ns_lookup+0x520/0x734 > >> > [ 0.602134] LR is at acpi_ns_lookup+0x4a4/0x734 > >> > [ 0.606693] pc : [<ffff0000083b8b10>] lr : [<ffff0000083b8a94>] pstate: 60000045 > >> > [ 0.614145] sp : ffff800001efb8b0 > >> > [ 0.617478] x29: ffff800001efb8c0 x28: 000000000000001b > >> > [ 0.622829] x27: 0000000000000001 x26: 0000000000000000 > >> > [ 0.628181] x25: ffff800001efb9e8 x24: ffff000008a10000 > >> > [ 0.633531] x23: 0000000000000001 x22: 0000000000000001 > >> > [ 0.638881] x21: ffff000008724000 x20: 000000000000001b > >> > [ 0.644230] x19: ffff0000080521e7 x18: 000000000000000d > >> > [ 0.649580] x17: 00000000000038ff x16: 0000000000000002 > >> > [ 0.654929] x15: 0000000000000007 x14: 0000000000007fff > >> > [ 0.660278] x13: ffffff0000000000 x12: 0000000000000018 > >> > [ 0.665627] x11: 000000001fffd200 x10: 00000000ffffff76 > >> > [ 0.670978] x9 : 000000000000005f x8 : ffff000008725fa8 > >> > [ 0.676328] x7 : ffff000008a8df70 x6 : ffff000008a8df70 > >> > [ 0.681679] x5 : ffff000008a8d000 x4 : 0000000000000010 > >> > [ 0.687027] x3 : 0000000000000010 x2 : 000000000000000c > >> > [ 0.692378] x1 : 0000000000000006 x0 : 0000000000000000 > >> > ... > >> > [ 1.262235] [<ffff0000083b8b10>] acpi_ns_lookup+0x520/0x734 > >> > [ 1.267845] [<ffff0000083a7160>] acpi_ds_load1_begin_op+0x174/0x4fc > >> > [ 1.274156] [<ffff0000083c1f4c>] acpi_ps_build_named_op+0xf8/0x220 > >> > [ 1.280380] [<ffff0000083c227c>] acpi_ps_create_op+0x208/0x33c > >> > [ 1.286254] [<ffff0000083c1820>] acpi_ps_parse_loop+0x204/0x838 > >> > [ 1.292215] [<ffff0000083c2fd4>] acpi_ps_parse_aml+0x1bc/0x42c > >> > [ 1.298090] [<ffff0000083bc6e8>] acpi_ns_one_complete_parse+0x1e8/0x22c > >> > [ 1.304753] [<ffff0000083bc7b8>] acpi_ns_parse_table+0x8c/0x128 > >> > [ 1.310716] [<ffff0000083bb8fc>] acpi_ns_load_table+0xc0/0x1e8 > >> > [ 1.316591] [<ffff0000083c9068>] acpi_tb_load_namespace+0xf8/0x2e8 > >> > [ 1.322818] [<ffff000008984128>] acpi_load_tables+0x7c/0x110 > >> > [ 1.328516] [<ffff000008982ea4>] acpi_init+0x90/0x2c0 > >> > [ 1.333603] [<ffff0000080819fc>] do_one_initcall+0x38/0x12c > >> > [ 1.339215] [<ffff000008960cd4>] kernel_init_freeable+0x148/0x1ec > >> > [ 1.345353] [<ffff0000086b7d30>] kernel_init+0x10/0xec > >> > [ 1.350529] [<ffff000008084e10>] ret_from_fork+0x10/0x40 > >> > [ 1.355878] Code: b9009fbc 2a00037b 36380057 3219037b (b9400260) > >> > [ 1.362035] ---[ end trace 03381e5eb0a24de4 ]--- > >> > [ 1.366691] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b > >> > > >> > With 'efi=debug', we can see those ACPI regions loaded by firmware on > >> > that board as: > >> > [ 0.000000] efi: 0x0083ff1b5000-0x0083ff1c2fff [ACPI Reclaim Memory| | | | | | | | |WB|WT|WC|UC]* > >> > [ 0.000000] efi: 0x0083ff223000-0x0083ff224fff [ACPI Memory NVS | | | | | | | | |WB|WT|WC|UC]* > >> > > >> > This patch is trying to address the above issues by nomaping the region > >> > instead of removing it. > >> > > >> > Signed-off-by: Dennis Chen <dennis.chen@arm.com> > >> > Cc: Catalin Marinas <catalin.marinas@arm.com> > >> > Cc: Steve Capper <steve.capper@arm.com> > >> > Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> > >> > Cc: Will Deacon <will.deacon@arm.com> > >> > Cc: Mark Rutland <mark.rutland@arm.com> > >> > Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> > >> > Cc: Matt Fleming <matt@codeblueprint.co.uk> > >> > Cc: linux-mm@kvack.org > >> > Cc: linux-acpi@vger.kernel.org > >> > Cc: linux-efi@vger.kernel.org > >> > --- > >> > Changes in v2: > >> > Update the commit message and remove the memblock_is_map_memory() check > >> > according to the suggestion from Mark Rutland. > >> > > >> > arch/arm64/mm/init.c | 9 +++++---- > >> > 1 file changed, 5 insertions(+), 4 deletions(-) > >> > > >> > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > >> > index d45f862..6af2456 100644 > >> > --- a/arch/arm64/mm/init.c > >> > +++ b/arch/arm64/mm/init.c > >> > @@ -222,12 +222,13 @@ void __init arm64_memblock_init(void) > >> > > >> > /* > >> > * Apply the memory limit if it was set. Since the kernel may be loaded > >> > - * high up in memory, add back the kernel region that must be accessible > >> > - * via the linear mapping. > >> > + * in the memory regions above the limit, so we need to clear the > >> > + * MEMBLOCK_NOMAP flag of this region to make it can be accessible via > >> > + * the linear mapping. > >> > */ > >> > if (memory_limit != (phys_addr_t)ULLONG_MAX) { > >> > - memblock_enforce_memory_limit(memory_limit); > >> > - memblock_add(__pa(_text), (u64)(_end - _text)); > >> > + memblock_mem_limit_mark_nomap(memory_limit); > >> > + memblock_clear_nomap(__pa(_text), (u64)(_end - _text)); > >> > >> Up until now, we have ignored the effect of having NOMAP memblocks on > >> the return values of functions like memblock_phys_mem_size() and > >> memblock_mem_size(), since they could reasonably be expected to cover > >> only a small slice of all available memory. However, after applying > >> this patch, it may well be the case that most of memory is marked > >> NOMAP, and these functions will cease to work as expected. > >> > > Hi Ard, I noticed these inconsistences as you mentioned, but seems the > > available memory is limited correctly. For this case('mem='), will it bring > > some substantive side effects except that some log messages maybe confusing? > > That is exactly the question that needs answering before we can merge > these patches. I know we consider mem= a development hack, but the > intent is to make it appear to the kernel as if only a smaller amount > of memory is available to the kernel, and this is signficantly > different from having memblock_mem_size() et al return much larger > values than what is actually available. Perhaps this doesn't matter at > all, but it is something we must discuss before proceeding with these > changes. > Indeed. So let's go back to the method below... > > >> > >> This means NOMAP is really only suited to punch some holes into the > >> kernel direct mapping, and so implementing the memory limit by marking > >> everything NOMAP is not the way to go. Instead, we should probably > >> reorder the init sequence so that the regions that are reserved in the > >> UEFI memory map are declared and marked NOMAP [again] after applying > >> the memory limit in the old way. > >> > > Before this patch, I have another one addressing the same issue [1], with > > that patch we'll not have these inconsistences, but it looks like a little > > bit complicated, so it becomes current one. Any comments about that? > > > > [1]http://lists.infradead.org/pipermail/linux-arm-kernel/2016-June/438443.html > > > > The problem caused by mem= is that it removes regions that are marked > NOMAP. So instead of marking everything above the limit NOMAP, I would > much rather see an alternative implementation of > memblock_enforce_memory_limit() that enforces the mem= limit by only > removing memblocks that have to NOMAP flag cleared, and leaving the > NOMAP ones where they are. > At least for me, this approach will mitigate the inconsistence in some degree while keeping the similar logic as it was, so I will post an updated version patch soon. Thanks, Dennis >
On Fri, Jun 24, 2016 at 04:12:02PM +0200, Ard Biesheuvel wrote: > On 24 June 2016 at 14:01, Dennis Chen <dennis.chen@arm.com> wrote: > > On Fri, Jun 24, 2016 at 12:43:52PM +0200, Ard Biesheuvel wrote: > >> On 24 June 2016 at 05:13, Dennis Chen <dennis.chen@arm.com> wrote: > >> > /* > >> > * Apply the memory limit if it was set. Since the kernel may be loaded > >> > - * high up in memory, add back the kernel region that must be accessible > >> > - * via the linear mapping. > >> > + * in the memory regions above the limit, so we need to clear the > >> > + * MEMBLOCK_NOMAP flag of this region to make it can be accessible via > >> > + * the linear mapping. > >> > */ > >> > if (memory_limit != (phys_addr_t)ULLONG_MAX) { > >> > - memblock_enforce_memory_limit(memory_limit); > >> > - memblock_add(__pa(_text), (u64)(_end - _text)); > >> > + memblock_mem_limit_mark_nomap(memory_limit); > >> > + memblock_clear_nomap(__pa(_text), (u64)(_end - _text)); > >> > >> Up until now, we have ignored the effect of having NOMAP memblocks on > >> the return values of functions like memblock_phys_mem_size() and > >> memblock_mem_size(), since they could reasonably be expected to cover > >> only a small slice of all available memory. However, after applying > >> this patch, it may well be the case that most of memory is marked > >> NOMAP, and these functions will cease to work as expected. > >> > > Hi Ard, I noticed these inconsistences as you mentioned, but seems the > > available memory is limited correctly. For this case('mem='), will it bring > > some substantive side effects except that some log messages maybe confusing? > > That is exactly the question that needs answering before we can merge > these patches. I know we consider mem= a development hack, but the > intent is to make it appear to the kernel as if only a smaller amount > of memory is available to the kernel, and this is signficantly > different from having memblock_mem_size() et al return much larger > values than what is actually available. Perhaps this doesn't matter at > all, but it is something we must discuss before proceeding with these > changes. Yeah, I think we need to figure out precisely what the expected semantics are. From taking a look, memblock_mem_size() is only used by arch/x86. In reserve_initrd, it's used to determine the amount of *free* memory, but it counts reserved (and nomap) regions, so that doesn't feel right regardless. For reserve_crashkernel_low it's not immediately clear to me what it should do, as I've not gone digging. There are many memblock_end_of_DRAM() users, mostly in arch code. We (arm64) use it to determine the size of the linear map, and effectively need it to be the limit for what should be mapped, which could/should exclude nomap. I've not yet dug into the rest, so I don't know whether that holds. > >> This means NOMAP is really only suited to punch some holes into the > >> kernel direct mapping, and so implementing the memory limit by marking > >> everything NOMAP is not the way to go. Instead, we should probably > >> reorder the init sequence so that the regions that are reserved in the > >> UEFI memory map are declared and marked NOMAP [again] after applying > >> the memory limit in the old way. > >> > > Before this patch, I have another one addressing the same issue [1], with > > that patch we'll not have these inconsistences, but it looks like a little > > bit complicated, so it becomes current one. Any comments about that? > > > > [1]http://lists.infradead.org/pipermail/linux-arm-kernel/2016-June/438443.html > > The problem caused by mem= is that it removes regions that are marked > NOMAP. So instead of marking everything above the limit NOMAP, I would > much rather see an alternative implementation of > memblock_enforce_memory_limit() that enforces the mem= limit by only > removing memblocks that have to NOMAP flag cleared, and leaving the > NOMAP ones where they are. That would work for me. Thanks, Mark.
On Mon, Jun 27, 2016 at 10:53:18AM +0100, Mark Rutland wrote: > On Fri, Jun 24, 2016 at 04:12:02PM +0200, Ard Biesheuvel wrote: > > On 24 June 2016 at 14:01, Dennis Chen <dennis.chen@arm.com> wrote: > > > On Fri, Jun 24, 2016 at 12:43:52PM +0200, Ard Biesheuvel wrote: > > >> On 24 June 2016 at 05:13, Dennis Chen <dennis.chen@arm.com> wrote: > > >> > /* > > >> > * Apply the memory limit if it was set. Since the kernel may be loaded > > >> > - * high up in memory, add back the kernel region that must be accessible > > >> > - * via the linear mapping. > > >> > + * in the memory regions above the limit, so we need to clear the > > >> > + * MEMBLOCK_NOMAP flag of this region to make it can be accessible via > > >> > + * the linear mapping. > > >> > */ > > >> > if (memory_limit != (phys_addr_t)ULLONG_MAX) { > > >> > - memblock_enforce_memory_limit(memory_limit); > > >> > - memblock_add(__pa(_text), (u64)(_end - _text)); > > >> > + memblock_mem_limit_mark_nomap(memory_limit); > > >> > + memblock_clear_nomap(__pa(_text), (u64)(_end - _text)); > > >> > > >> Up until now, we have ignored the effect of having NOMAP memblocks on > > >> the return values of functions like memblock_phys_mem_size() and > > >> memblock_mem_size(), since they could reasonably be expected to cover > > >> only a small slice of all available memory. However, after applying > > >> this patch, it may well be the case that most of memory is marked > > >> NOMAP, and these functions will cease to work as expected. > > >> > > > Hi Ard, I noticed these inconsistences as you mentioned, but seems the > > > available memory is limited correctly. For this case('mem='), will it bring > > > some substantive side effects except that some log messages maybe confusing? > > > > That is exactly the question that needs answering before we can merge > > these patches. I know we consider mem= a development hack, but the > > intent is to make it appear to the kernel as if only a smaller amount > > of memory is available to the kernel, and this is signficantly > > different from having memblock_mem_size() et al return much larger > > values than what is actually available. Perhaps this doesn't matter at > > all, but it is something we must discuss before proceeding with these > > changes. > > Yeah, I think we need to figure out precisely what the expected > semantics are. > > From taking a look, memblock_mem_size() is only used by arch/x86. In > reserve_initrd, it's used to determine the amount of *free* memory, but > it counts reserved (and nomap) regions, so that doesn't feel right > regardless. For reserve_crashkernel_low it's not immediately clear to me > what it should do, as I've not gone digging. > After rough digging go, memblock_mem_size() used by arch/x86 to calculate the size of a segment of direct mapping physical memory, it only counts on memory memblock region regardless of the flag of that region, so from this point, if we have a segment of memory marked as NOMAP, memblock_mem_size() will still take its size into the total size and have it a direct mapped. IMO memblock_mem_size() is not used to determine the amount of *free*, it just to determine the amount of mem that can be mapped directly, so it's reasonable to count reserved regions. > > There are many memblock_end_of_DRAM() users, mostly in arch code. We > (arm64) use it to determine the size of the linear map, and effectively > need it to be the limit for what should be mapped, which could/should > exclude nomap. I've not yet dug into the rest, so I don't know whether > that holds. > we will use memblock_end_of_DRAM() to get the top boundary of the linear mapping, given some memblock region is NOMAP, so some holes will be punched into the linear mapping zone just as you mentioned those NOMAP should be excluded. As my understanding, NOMAP regions only have possible potential side effect to count the mem size such as memblock_mem_size > > > >> This means NOMAP is really only suited to punch some holes into the > > >> kernel direct mapping, and so implementing the memory limit by marking > > >> everything NOMAP is not the way to go. Instead, we should probably > > >> reorder the init sequence so that the regions that are reserved in the > > >> UEFI memory map are declared and marked NOMAP [again] after applying > > >> the memory limit in the old way. > > >> > > > Before this patch, I have another one addressing the same issue [1], with > > > that patch we'll not have these inconsistences, but it looks like a little > > > bit complicated, so it becomes current one. Any comments about that? > > > > > > [1]http://lists.infradead.org/pipermail/linux-arm-kernel/2016-June/438443.html > > > > The problem caused by mem= is that it removes regions that are marked > > NOMAP. So instead of marking everything above the limit NOMAP, I would > > much rather see an alternative implementation of > > memblock_enforce_memory_limit() that enforces the mem= limit by only > > removing memblocks that have to NOMAP flag cleared, and leaving the > > NOMAP ones where they are. > > That would work for me. > > Thanks, > Mark. >
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c index d45f862..6af2456 100644 --- a/arch/arm64/mm/init.c +++ b/arch/arm64/mm/init.c @@ -222,12 +222,13 @@ void __init arm64_memblock_init(void) /* * Apply the memory limit if it was set. Since the kernel may be loaded - * high up in memory, add back the kernel region that must be accessible - * via the linear mapping. + * in the memory regions above the limit, so we need to clear the + * MEMBLOCK_NOMAP flag of this region to make it can be accessible via + * the linear mapping. */ if (memory_limit != (phys_addr_t)ULLONG_MAX) { - memblock_enforce_memory_limit(memory_limit); - memblock_add(__pa(_text), (u64)(_end - _text)); + memblock_mem_limit_mark_nomap(memory_limit); + memblock_clear_nomap(__pa(_text), (u64)(_end - _text)); } if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && initrd_start) {
When booting an ACPI enabled kernel with 'mem=', probably the ACPI data regions loaded by firmware will beyond the limit of the memory, in this case we need to nomap the region above the limit while not removing it from memblock, because once region removed from memblock, the ACPI will think that region is not a normal memory and map it as device type memory accordingly. Since the ACPI core will produce non-alignment access when paring AML data stream, hence result in alignment fault upon the io mapped memory space. For example, below is an alignment exception observed on softIron board when booting the kernel with 'acpi=force mem=8G': ... [ 0.542475] Unable to handle kernel paging request at virtual address ffff0000080521e7 [ 0.550457] pgd = ffff000008aa0000 [ 0.553880] [ffff0000080521e7] *pgd=000000801fffe003, *pud=000000801fffd003, *pmd=000000801fffc003, *pte=00e80083ff1c1707 [ 0.564939] Internal error: Oops: 96000021 [#1] PREEMPT SMP [ 0.570553] Modules linked in: [ 0.573626] CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.7.0-rc3-next-20160616+ #172 [ 0.581344] Hardware name: AMD Overdrive/Supercharger/Default string, BIOS ROD1001A 02/09/2016 [ 0.590025] task: ffff800001ef0000 ti: ffff800001ef8000 task.ti: ffff800001ef8000 [ 0.597571] PC is at acpi_ns_lookup+0x520/0x734 [ 0.602134] LR is at acpi_ns_lookup+0x4a4/0x734 [ 0.606693] pc : [<ffff0000083b8b10>] lr : [<ffff0000083b8a94>] pstate: 60000045 [ 0.614145] sp : ffff800001efb8b0 [ 0.617478] x29: ffff800001efb8c0 x28: 000000000000001b [ 0.622829] x27: 0000000000000001 x26: 0000000000000000 [ 0.628181] x25: ffff800001efb9e8 x24: ffff000008a10000 [ 0.633531] x23: 0000000000000001 x22: 0000000000000001 [ 0.638881] x21: ffff000008724000 x20: 000000000000001b [ 0.644230] x19: ffff0000080521e7 x18: 000000000000000d [ 0.649580] x17: 00000000000038ff x16: 0000000000000002 [ 0.654929] x15: 0000000000000007 x14: 0000000000007fff [ 0.660278] x13: ffffff0000000000 x12: 0000000000000018 [ 0.665627] x11: 000000001fffd200 x10: 00000000ffffff76 [ 0.670978] x9 : 000000000000005f x8 : ffff000008725fa8 [ 0.676328] x7 : ffff000008a8df70 x6 : ffff000008a8df70 [ 0.681679] x5 : ffff000008a8d000 x4 : 0000000000000010 [ 0.687027] x3 : 0000000000000010 x2 : 000000000000000c [ 0.692378] x1 : 0000000000000006 x0 : 0000000000000000 ... [ 1.262235] [<ffff0000083b8b10>] acpi_ns_lookup+0x520/0x734 [ 1.267845] [<ffff0000083a7160>] acpi_ds_load1_begin_op+0x174/0x4fc [ 1.274156] [<ffff0000083c1f4c>] acpi_ps_build_named_op+0xf8/0x220 [ 1.280380] [<ffff0000083c227c>] acpi_ps_create_op+0x208/0x33c [ 1.286254] [<ffff0000083c1820>] acpi_ps_parse_loop+0x204/0x838 [ 1.292215] [<ffff0000083c2fd4>] acpi_ps_parse_aml+0x1bc/0x42c [ 1.298090] [<ffff0000083bc6e8>] acpi_ns_one_complete_parse+0x1e8/0x22c [ 1.304753] [<ffff0000083bc7b8>] acpi_ns_parse_table+0x8c/0x128 [ 1.310716] [<ffff0000083bb8fc>] acpi_ns_load_table+0xc0/0x1e8 [ 1.316591] [<ffff0000083c9068>] acpi_tb_load_namespace+0xf8/0x2e8 [ 1.322818] [<ffff000008984128>] acpi_load_tables+0x7c/0x110 [ 1.328516] [<ffff000008982ea4>] acpi_init+0x90/0x2c0 [ 1.333603] [<ffff0000080819fc>] do_one_initcall+0x38/0x12c [ 1.339215] [<ffff000008960cd4>] kernel_init_freeable+0x148/0x1ec [ 1.345353] [<ffff0000086b7d30>] kernel_init+0x10/0xec [ 1.350529] [<ffff000008084e10>] ret_from_fork+0x10/0x40 [ 1.355878] Code: b9009fbc 2a00037b 36380057 3219037b (b9400260) [ 1.362035] ---[ end trace 03381e5eb0a24de4 ]--- [ 1.366691] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b With 'efi=debug', we can see those ACPI regions loaded by firmware on that board as: [ 0.000000] efi: 0x0083ff1b5000-0x0083ff1c2fff [ACPI Reclaim Memory| | | | | | | | |WB|WT|WC|UC]* [ 0.000000] efi: 0x0083ff223000-0x0083ff224fff [ACPI Memory NVS | | | | | | | | |WB|WT|WC|UC]* This patch is trying to address the above issues by nomaping the region instead of removing it. Signed-off-by: Dennis Chen <dennis.chen@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Steve Capper <steve.capper@arm.com> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Cc: Matt Fleming <matt@codeblueprint.co.uk> Cc: linux-mm@kvack.org Cc: linux-acpi@vger.kernel.org Cc: linux-efi@vger.kernel.org --- Changes in v2: Update the commit message and remove the memblock_is_map_memory() check according to the suggestion from Mark Rutland. arch/arm64/mm/init.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-)