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@xxxxxxxxxx>
> ---
> 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
