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Date: Sun, 11 Nov 2018 21:45:48 -0500
From: Qian Cai <cai@....us>
To: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc: linux-mm@...ck.org, linux-efi@...r.kernel.org, will.deacon@....com,
linux kernel <linux-kernel@...r.kernel.org>,
Marc Zyngier <marc.zyngier@....com>,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] efi: permit calling efi_mem_reserve_persistent from
atomic context
> On Nov 9, 2018, at 9:45 PM, Qian Cai <cai@....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@...aro.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 ]---
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