Patchwork efi: permit calling efi_mem_reserve_persistent from atomic context

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Submitter Ard Biesheuvel
Date Nov. 8, 2018, 6:05 p.m.
Message ID <20181108180511.30239-1-ard.biesheuvel@linaro.org>
Download mbox | patch
Permalink /patch/652705/
State New
Headers show

Comments

Ard Biesheuvel - Nov. 8, 2018, 6:05 p.m.
Currently, efi_mem_reserve_persistent() may not be called from atomic
context, since both the kmalloc() call and the memremap() call may
sleep.

The kmalloc() call is easy enough to fix, but the memremap() call
needs to be moved into an init hook since we cannot control the
memory allocation behavior of memremap() at the call site.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
 drivers/firmware/efi/efi.c | 31 +++++++++++++++++++------------
 1 file changed, 19 insertions(+), 12 deletions(-)
Qian Cai - Nov. 8, 2018, 8:48 p.m.
On Thu, 2018-11-08 at 19:05 +0100, Ard Biesheuvel wrote:
> Currently, efi_mem_reserve_persistent() may not be called from atomic
> context, since both the kmalloc() call and the memremap() call may
> sleep.
> 
> The kmalloc() call is easy enough to fix, but the memremap() call
> needs to be moved into an init hook since we cannot control the
> memory allocation behavior of memremap() at the call site.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Tested-by: Qian Cai <cai@gmx.us>
Qian Cai - Nov. 10, 2018, 2:45 a.m.
On 11/8/18 at 1:05 PM, Ard Biesheuvel wrote:

> Currently, efi_mem_reserve_persistent() may not be called from atomic
> context, since both the kmalloc() call and the memremap() call may
> sleep.
> 
> The kmalloc() call is easy enough to fix, but the memremap() call
> needs to be moved into an init hook since we cannot control the
> memory allocation behavior of memremap() at the call site.
> 
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
>  drivers/firmware/efi/efi.c | 31 +++++++++++++++++++------------
>  1 file changed, 19 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index 249eb70691b0..cfc876e0b67b 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -963,36 +963,43 @@ bool efi_is_table_address(unsigned long phys_addr)
>  }
>  
>  static DEFINE_SPINLOCK(efi_mem_reserve_persistent_lock);
> +static struct linux_efi_memreserve *efi_memreserve_root __ro_after_init;
>  
>  int efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
>  {
> -	struct linux_efi_memreserve *rsv, *parent;
> +	struct linux_efi_memreserve *rsv;
>  
> -	if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)
> +	if (!efi_memreserve_root)
>  		return -ENODEV;
>  
> -	rsv = kmalloc(sizeof(*rsv), GFP_KERNEL);
> +	rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC);
>  	if (!rsv)
>  		return -ENOMEM;
>  
> -	parent = memremap(efi.mem_reserve, sizeof(*rsv), MEMREMAP_WB);
> -	if (!parent) {
> -		kfree(rsv);
> -		return -ENOMEM;
> -	}
> -
>  	rsv->base = addr;
>  	rsv->size = size;
>  
>  	spin_lock(&efi_mem_reserve_persistent_lock);
> -	rsv->next = parent->next;
> -	parent->next = __pa(rsv);
> +	rsv->next = efi_memreserve_root->next;
> +	efi_memreserve_root->next = __pa(rsv);
>  	spin_unlock(&efi_mem_reserve_persistent_lock);
>  
> -	memunmap(parent);
> +	return 0;
> +}
>  
> +static int __init efi_memreserve_root_init(void)
> +{
> +	if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)
> +		return -ENODEV;
> +
> +	efi_memreserve_root = memremap(efi.mem_reserve,
> +				       sizeof(*efi_memreserve_root),
> +				       MEMREMAP_WB);
> +	if (!efi_memreserve_root)
> +		return -ENOMEM;
>  	return 0;
>  }
> +early_initcall(efi_memreserve_root_init);
>  
>  #ifdef CONFIG_KEXEC
>  static int update_efi_random_seed(struct notifier_block *nb,
> -- 
> 2.19.1
BTW, I won’t be able to apply this patch on top of this series [1]. After applied that series, the original BUG sleep from atomic is gone as well as two other GIC warnings. Do you think a new patch is needed here?

[1] https://www.spinics.net/lists/arm-kernel/msg685751.html
Qian Cai - Nov. 12, 2018, 2:45 a.m.
> On Nov 9, 2018, at 9:45 PM, Qian Cai <cai@gmx.us> wrote:
> 
> 
> On 11/8/18 at 1:05 PM, Ard Biesheuvel wrote:
> 
>> Currently, efi_mem_reserve_persistent() may not be called from atomic
>> context, since both the kmalloc() call and the memremap() call may
>> sleep.
>> 
>> The kmalloc() call is easy enough to fix, but the memremap() call
>> needs to be moved into an init hook since we cannot control the
>> memory allocation behavior of memremap() at the call site.
>> 
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>> ---
>> drivers/firmware/efi/efi.c | 31 +++++++++++++++++++------------
>> 1 file changed, 19 insertions(+), 12 deletions(-)
>> 
>> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
>> index 249eb70691b0..cfc876e0b67b 100644
>> --- a/drivers/firmware/efi/efi.c
>> +++ b/drivers/firmware/efi/efi.c
>> @@ -963,36 +963,43 @@ bool efi_is_table_address(unsigned long phys_addr)
>> }
>> 
>> static DEFINE_SPINLOCK(efi_mem_reserve_persistent_lock);
>> +static struct linux_efi_memreserve *efi_memreserve_root __ro_after_init;
>> 
>> int efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
>> {
>> -	struct linux_efi_memreserve *rsv, *parent;
>> +	struct linux_efi_memreserve *rsv;
>> 
>> -	if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)
>> +	if (!efi_memreserve_root)
>> 		return -ENODEV;
>> 
>> -	rsv = kmalloc(sizeof(*rsv), GFP_KERNEL);
>> +	rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC);
>> 	if (!rsv)
>> 		return -ENOMEM;
>> 
>> -	parent = memremap(efi.mem_reserve, sizeof(*rsv), MEMREMAP_WB);
>> -	if (!parent) {
>> -		kfree(rsv);
>> -		return -ENOMEM;
>> -	}
>> -
>> 	rsv->base = addr;
>> 	rsv->size = size;
>> 
>> 	spin_lock(&efi_mem_reserve_persistent_lock);
>> -	rsv->next = parent->next;
>> -	parent->next = __pa(rsv);
>> +	rsv->next = efi_memreserve_root->next;
>> +	efi_memreserve_root->next = __pa(rsv);
>> 	spin_unlock(&efi_mem_reserve_persistent_lock);
>> 
>> -	memunmap(parent);
>> +	return 0;
>> +}
>> 
>> +static int __init efi_memreserve_root_init(void)
>> +{
>> +	if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)
>> +		return -ENODEV;
>> +
>> +	efi_memreserve_root = memremap(efi.mem_reserve,
>> +				       sizeof(*efi_memreserve_root),
>> +				       MEMREMAP_WB);
>> +	if (!efi_memreserve_root)
>> +		return -ENOMEM;
>> 	return 0;
>> }
>> +early_initcall(efi_memreserve_root_init);
>> 
>> #ifdef CONFIG_KEXEC
>> static int update_efi_random_seed(struct notifier_block *nb,
>> -- 
>> 2.19.1
> BTW, I won’t be able to apply this patch on top of this series [1]. After applied that series, the original BUG sleep from atomic is gone as well as two other GIC warnings. Do you think a new patch is needed here?
> 
> [1] https://www.spinics.net/lists/arm-kernel/msg685751.html
OK, I was able to apply this patch on top of latest mainline (ccda4af0f4b9)
which also include one patch (1/6) from the above series,

However, the efi-related patches from the series (4/6, 5/6, and 6/6) are no
longer able to be cleanly applied. 

As the results, the above patch did fix the original BUG: sleep from atomic,
but it introduces 2 new warnings.

[    0.000000] WARNING: CPU: 0 PID: 0 at drivers/irqchip/irq-gic-v3-its.c:1696 its_init+0x494/0x7e8
[    0.000000] Modules linked in:
[    0.000000] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.20.0-rc2+ #11
[    0.000000] pstate: 00000085 (nzcv daIf -PAN -UAO)
[    0.000000] pc : its_init+0x494/0x7e8
[    0.000000] lr : its_init+0x490/0x7e8
[    0.000000] sp : ffff20000a0c7a60
[    0.000000] x29: ffff20000a0c7a60 x28: 1fffe40001418f6e 
[    0.000000] x27: ffff20000a1061a8 x26: ffff8016c0fb0000 
[    0.000000] x25: ffff20000a3d2300 x24: ffff20000c542000 
[    0.000000] x23: 00000016c0fb0000 x22: ffff20000a1061a8 
[    0.000000] x21: 1fffe40001418f5e x20: ffff20000c542fa0 
[    0.000000] x19: ffff2000091c1be0 x18: 000000000000003f 
[    0.000000] x17: 00000000001bb6ad x16: 0000000000000000 
[    0.000000] x15: 0000000000007fff x14: 6166306336314020 
[    0.000000] x13: 736e6f697463656c x12: ffff1002d81f8000 
[    0.000000] x11: 1ffff002d81f7fff x10: ffff1002d81f7fff 
[    0.000000] x9 : 0000000000000000 x8 : ffff8016c0fc0000 
[    0.000000] x7 : a2a2a2a2a2a2a2a2 x6 : ffff8016c0fbffff 
[    0.000000] x5 : ffff1002d81f8000 x4 : dfff200000000000 
[    0.000000] x3 : 000000000000003f x2 : 000000000000ffff 
[    0.000000] x1 : 0000000000010000 x0 : 00000000ffffffed 
[    0.000000] Call trace:
[    0.000000]  its_init+0x494/0x7e8
[    0.000000]  gic_init_bases+0x2c0/0x2e0
[    0.000000]  gic_acpi_init+0x180/0x2ac
[    0.000000]  acpi_match_madt+0x5c/0x98
[    0.000000]  acpi_table_parse_entries_array+0x1e8/0x2ec
[    0.000000]  acpi_table_parse_entries+0xd8/0x10c
[    0.000000]  acpi_table_parse_madt+0x44/0x54
[    0.000000]  __acpi_probe_device_table+0xa8/0x10c
[    0.000000]  irqchip_init+0x38/0x40
[    0.000000]  init_IRQ+0xa0/0xdc
[    0.000000]  start_kernel+0x3b8/0x5a8
[    0.000000] irq event stamp: 0
[    0.000000] hardirqs last  enabled at (0): [<0000000000000000>]           (null)
[    0.000000] hardirqs last disabled at (0): [<0000000000000000>]           (null)
[    0.000000] softirqs last  enabled at (0): [<0000000000000000>]           (null)
[    0.000000] softirqs last disabled at (0): [<0000000000000000>]           (null)
[    0.000000] ---[ end trace 598902d30712b79b ]---
[    0.000000] GICv3: using LPI property table @0x00000016c0fb0000
[    0.000000] ITS: Using DirectLPI for VPE invalidation
[    0.000000] ITS: Enabling GICv4 support
[    0.000000] WARNING: CPU: 0 PID: 0 at drivers/irqchip/irq-gic-v3-its.c:2096 its_cpu_init_lpis+0x400/0x428
[    0.000000] Modules linked in:
[    0.000000] CPU: 0 PID: 0 Comm: swapper/0 Tainted: G        W         4.20.0-rc2+ #11
[    0.000000] pstate: 00000085 (nzcv daIf -PAN -UAO)
[    0.000000] pc : its_cpu_init_lpis+0x400/0x428
[    0.000000] lr : its_cpu_init_lpis+0x3fc/0x428
[    0.000000] sp : ffff20000a0c7a30
[    0.000000] x29: ffff20000a0c7a30 x28: ffff2000095d8000 
[    0.000000] x27: ffff20000a0f9848 x26: ffff20000c600000 
[    0.000000] x25: ffff2000095d85e0 x24: ffff20000c542000 
[    0.000000] x23: ffff20000a0c7ac0 x22: ffff7fe005b03f00 
[    0.000000] x21: ffff20000c542fa0 x20: 1fffe40001418f54 
[    0.000000] x19: 00000016c0fc0000 x18: 000000000000003f 
[    0.000000] x17: 0000000000000000 x16: ffff20000a10efc0 
[    0.000000] x15: 0000000000007fff x14: ffff20000992701c 
[    0.000000] x13: ffff20000991fafc x12: ffff040001418e0b 
[    0.000000] x11: 1fffe40001418e0a x10: ffff040001418e0a 
[    0.000000] x9 : dfff200000000000 x8 : dfff200000000000 
[    0.000000] x7 : dfff200000000000 x6 : 00000000f2f2f204 
[    0.000000] x5 : 00000000f1f1f1f1 x4 : dfff200000000000 
[    0.000000] x3 : 0000000000000010 x2 : 000000000000ffff 
[    0.000000] x1 : 0000000000010000 x0 : 00000000ffffffed 
[    0.000000] Call trace:
[    0.000000]  its_cpu_init_lpis+0x400/0x428
[    0.000000]  its_cpu_init+0x12c/0x290
[    0.000000]  gic_init_bases+0x2c4/0x2e0
[    0.000000]  gic_acpi_init+0x180/0x2ac
[    0.000000]  acpi_match_madt+0x5c/0x98
[    0.000000]  acpi_table_parse_entries_array+0x1e8/0x2ec
[    0.000000]  acpi_table_parse_entries+0xd8/0x10c
[    0.000000]  acpi_table_parse_madt+0x44/0x54
[    0.000000]  __acpi_probe_device_table+0xa8/0x10c
[    0.000000]  irqchip_init+0x38/0x40
[    0.000000]  init_IRQ+0xa0/0xdc
[    0.000000]  start_kernel+0x3b8/0x5a8
[    0.000000] irq event stamp: 0
[    0.000000] hardirqs last  enabled at (0): [<0000000000000000>]           (null)
[    0.000000] hardirqs last disabled at (0): [<0000000000000000>]           (null)
[    0.000000] softirqs last  enabled at (0): [<0000000000000000>]           (null)
[    0.000000] softirqs last disabled at (0): [<0000000000000000>]           (null)
[    0.000000] ---[ end trace 598902d30712b79c ]---
Marc Zyngier - Nov. 12, 2018, 8:32 a.m.
On Mon, 12 Nov 2018 02:45:48 +0000,
Qian Cai <cai@gmx.us> wrote:
> 
> 
> 
> > On Nov 9, 2018, at 9:45 PM, Qian Cai <cai@gmx.us> wrote:
> > 
> > 
> > On 11/8/18 at 1:05 PM, Ard Biesheuvel wrote:
> > 
> >> Currently, efi_mem_reserve_persistent() may not be called from atomic
> >> context, since both the kmalloc() call and the memremap() call may
> >> sleep.
> >> 
> >> The kmalloc() call is easy enough to fix, but the memremap() call
> >> needs to be moved into an init hook since we cannot control the
> >> memory allocation behavior of memremap() at the call site.
> >> 
> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> >> ---
> >> drivers/firmware/efi/efi.c | 31 +++++++++++++++++++------------
> >> 1 file changed, 19 insertions(+), 12 deletions(-)
> >> 
> >> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> >> index 249eb70691b0..cfc876e0b67b 100644
> >> --- a/drivers/firmware/efi/efi.c
> >> +++ b/drivers/firmware/efi/efi.c
> >> @@ -963,36 +963,43 @@ bool efi_is_table_address(unsigned long phys_addr)
> >> }
> >> 
> >> static DEFINE_SPINLOCK(efi_mem_reserve_persistent_lock);
> >> +static struct linux_efi_memreserve *efi_memreserve_root __ro_after_init;
> >> 
> >> int efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
> >> {
> >> -	struct linux_efi_memreserve *rsv, *parent;
> >> +	struct linux_efi_memreserve *rsv;
> >> 
> >> -	if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)
> >> +	if (!efi_memreserve_root)
> >> 		return -ENODEV;
> >> 
> >> -	rsv = kmalloc(sizeof(*rsv), GFP_KERNEL);
> >> +	rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC);
> >> 	if (!rsv)
> >> 		return -ENOMEM;
> >> 
> >> -	parent = memremap(efi.mem_reserve, sizeof(*rsv), MEMREMAP_WB);
> >> -	if (!parent) {
> >> -		kfree(rsv);
> >> -		return -ENOMEM;
> >> -	}
> >> -
> >> 	rsv->base = addr;
> >> 	rsv->size = size;
> >> 
> >> 	spin_lock(&efi_mem_reserve_persistent_lock);
> >> -	rsv->next = parent->next;
> >> -	parent->next = __pa(rsv);
> >> +	rsv->next = efi_memreserve_root->next;
> >> +	efi_memreserve_root->next = __pa(rsv);
> >> 	spin_unlock(&efi_mem_reserve_persistent_lock);
> >> 
> >> -	memunmap(parent);
> >> +	return 0;
> >> +}
> >> 
> >> +static int __init efi_memreserve_root_init(void)
> >> +{
> >> +	if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)
> >> +		return -ENODEV;
> >> +
> >> +	efi_memreserve_root = memremap(efi.mem_reserve,
> >> +				       sizeof(*efi_memreserve_root),
> >> +				       MEMREMAP_WB);
> >> +	if (!efi_memreserve_root)
> >> +		return -ENOMEM;
> >> 	return 0;
> >> }
> >> +early_initcall(efi_memreserve_root_init);
> >> 
> >> #ifdef CONFIG_KEXEC
> >> static int update_efi_random_seed(struct notifier_block *nb,
> >> -- 
> >> 2.19.1
> > BTW, I won’t be able to apply this patch on top of this series [1]. After applied that series, the original BUG sleep from atomic is gone as well as two other GIC warnings. Do you think a new patch is needed here?
> > 
> > [1] https://www.spinics.net/lists/arm-kernel/msg685751.html
> OK, I was able to apply this patch on top of latest mainline (ccda4af0f4b9)
> which also include one patch (1/6) from the above series,
> 
> However, the efi-related patches from the series (4/6, 5/6, and 6/6) are no
> longer able to be cleanly applied. 
> 
> As the results, the above patch did fix the original BUG: sleep from atomic,
> but it introduces 2 new warnings.

[...]

These are the warnings you've already reported, aren't they? And we've
established that if you apply the whole series, everything work as
intended at least on the GIC side (the timer issue is a different
story altogether).

Or am I missing something?

Thanks,

	M.
Qian Cai - Nov. 12, 2018, 12:14 p.m.
On 11/12/18 at 3:32 AM, Marc Zyngier wrote:

> On Mon, 12 Nov 2018 02:45:48 +0000,
> Qian Cai <cai@gmx.us> wrote:
> > 
> > 
> > 
> > > On Nov 9, 2018, at 9:45 PM, Qian Cai <cai@gmx.us> wrote:
> > > 
> > > 
> > > On 11/8/18 at 1:05 PM, Ard Biesheuvel wrote:
> > > 
> > >> Currently, efi_mem_reserve_persistent() may not be called from atomic
> > >> context, since both the kmalloc() call and the memremap() call may
> > >> sleep.
> > >> 
> > >> The kmalloc() call is easy enough to fix, but the memremap() call
> > >> needs to be moved into an init hook since we cannot control the
> > >> memory allocation behavior of memremap() at the call site.
> > >> 
> > >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> > >> ---
> > >> drivers/firmware/efi/efi.c | 31 +++++++++++++++++++------------
> > >> 1 file changed, 19 insertions(+), 12 deletions(-)
> > >> 
> > >> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> > >> index 249eb70691b0..cfc876e0b67b 100644
> > >> --- a/drivers/firmware/efi/efi.c
> > >> +++ b/drivers/firmware/efi/efi.c
> > >> @@ -963,36 +963,43 @@ bool efi_is_table_address(unsigned long phys_addr)
> > >> }
> > >> 
> > >> static DEFINE_SPINLOCK(efi_mem_reserve_persistent_lock);
> > >> +static struct linux_efi_memreserve *efi_memreserve_root __ro_after_init;
> > >> 
> > >> int efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
> > >> {
> > >> -	struct linux_efi_memreserve *rsv, *parent;
> > >> +	struct linux_efi_memreserve *rsv;
> > >> 
> > >> -	if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)
> > >> +	if (!efi_memreserve_root)
> > >> 		return -ENODEV;
> > >> 
> > >> -	rsv = kmalloc(sizeof(*rsv), GFP_KERNEL);
> > >> +	rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC);
> > >> 	if (!rsv)
> > >> 		return -ENOMEM;
> > >> 
> > >> -	parent = memremap(efi.mem_reserve, sizeof(*rsv), MEMREMAP_WB);
> > >> -	if (!parent) {
> > >> -		kfree(rsv);
> > >> -		return -ENOMEM;
> > >> -	}
> > >> -
> > >> 	rsv->base = addr;
> > >> 	rsv->size = size;
> > >> 
> > >> 	spin_lock(&efi_mem_reserve_persistent_lock);
> > >> -	rsv->next = parent->next;
> > >> -	parent->next = __pa(rsv);
> > >> +	rsv->next = efi_memreserve_root->next;
> > >> +	efi_memreserve_root->next = __pa(rsv);
> > >> 	spin_unlock(&efi_mem_reserve_persistent_lock);
> > >> 
> > >> -	memunmap(parent);
> > >> +	return 0;
> > >> +}
> > >> 
> > >> +static int __init efi_memreserve_root_init(void)
> > >> +{
> > >> +	if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)
> > >> +		return -ENODEV;
> > >> +
> > >> +	efi_memreserve_root = memremap(efi.mem_reserve,
> > >> +				       sizeof(*efi_memreserve_root),
> > >> +				       MEMREMAP_WB);
> > >> +	if (!efi_memreserve_root)
> > >> +		return -ENOMEM;
> > >> 	return 0;
> > >> }
> > >> +early_initcall(efi_memreserve_root_init);
> > >> 
> > >> #ifdef CONFIG_KEXEC
> > >> static int update_efi_random_seed(struct notifier_block *nb,
> > >> -- 
> > >> 2.19.1
> > > BTW, I won’t be able to apply this patch on top of this series [1]. After applied that series, the original BUG sleep from atomic is gone as well as two other GIC warnings. Do you think a new patch is needed here?
> > > 
> > > [1] https://www.spinics.net/lists/arm-kernel/msg685751.html
> > OK, I was able to apply this patch on top of latest mainline (ccda4af0f4b9)
> > which also include one patch (1/6) from the above series,
> > 
> > However, the efi-related patches from the series (4/6, 5/6, and 6/6) are no
> > longer able to be cleanly applied. 
> > 
> > As the results, the above patch did fix the original BUG: sleep from atomic,
> > but it introduces 2 new warnings.
> 
> [...]
> 
> These are the warnings you've already reported, aren't they? And we've
> established that if you apply the whole series, everything work as
> intended at least on the GIC side (the timer issue is a different
> story altogether).
> 
> Or am I missing something?
The problem is that I am not able to apply the whole  
series alone on top of the latest mainline (rc2) now to 
verify  it. Also, I won’t be able to apply the series and 
this patch together on top of rc1. There are conflicts 
between this patch and 4-6 of the series.

Originally, I said those GIC warnings are gone when
testing rc1 + the series, but I am not sure if it is just
dumb luck that also fix BUG: sleep from atomic. Make
sense?

Patch

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 249eb70691b0..cfc876e0b67b 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -963,36 +963,43 @@  bool efi_is_table_address(unsigned long phys_addr)
 }
 
 static DEFINE_SPINLOCK(efi_mem_reserve_persistent_lock);
+static struct linux_efi_memreserve *efi_memreserve_root __ro_after_init;
 
 int efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
 {
-	struct linux_efi_memreserve *rsv, *parent;
+	struct linux_efi_memreserve *rsv;
 
-	if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)
+	if (!efi_memreserve_root)
 		return -ENODEV;
 
-	rsv = kmalloc(sizeof(*rsv), GFP_KERNEL);
+	rsv = kmalloc(sizeof(*rsv), GFP_ATOMIC);
 	if (!rsv)
 		return -ENOMEM;
 
-	parent = memremap(efi.mem_reserve, sizeof(*rsv), MEMREMAP_WB);
-	if (!parent) {
-		kfree(rsv);
-		return -ENOMEM;
-	}
-
 	rsv->base = addr;
 	rsv->size = size;
 
 	spin_lock(&efi_mem_reserve_persistent_lock);
-	rsv->next = parent->next;
-	parent->next = __pa(rsv);
+	rsv->next = efi_memreserve_root->next;
+	efi_memreserve_root->next = __pa(rsv);
 	spin_unlock(&efi_mem_reserve_persistent_lock);
 
-	memunmap(parent);
+	return 0;
+}
 
+static int __init efi_memreserve_root_init(void)
+{
+	if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR)
+		return -ENODEV;
+
+	efi_memreserve_root = memremap(efi.mem_reserve,
+				       sizeof(*efi_memreserve_root),
+				       MEMREMAP_WB);
+	if (!efi_memreserve_root)
+		return -ENOMEM;
 	return 0;
 }
+early_initcall(efi_memreserve_root_init);
 
 #ifdef CONFIG_KEXEC
 static int update_efi_random_seed(struct notifier_block *nb,