Re: [PATCH] efi: Fix the size not consistent issue when unmapping memory map

Dave Young
2018-04-16T03:09:04Z

On 04/16/18 at 10:57am, Dave Young wrote:
> On 04/13/18 at 02:27pm, Lee, Chun-Yi wrote:
> > When using kdump, SOMETIMES the "size not consistent" warning message
> > shows up when the crash kernel boots with early_ioremap_debug parameter:
> >
> > WARNING: CPU: 0 PID: 0 at ../mm/early_ioremap.c:182 early_iounmap+0x4f/0x12c()
> > early_iounmap(ffffffffff200180, 00000118) [0] size not consistent 00000120
> >
> > The root cause is that the unmapping size of memory map doesn't
> > match with the original size when mapping:
> >
> > in __efi_memmap_init()
> > map.map = early_memremap(phys_map, data->size);
> >
> > in efi_memmap_unmap()
> > size = efi.memmap.desc_size * efi.memmap.nr_map;
> > early_memunmap(efi.memmap.map, size);
> >
> > But the efi.memmap.nr_map is from __efi_memmap_init(). The remainder
> > of size was discarded when calculating the nr_map:
> > map.nr_map = data->size / data->desc_size;
> >
> > When the original size of memory map region does not equal to the
> > result of multiplication. The "size not consistent" warning
> > will be triggered.
> >
> > This issue sometimes was hit by kdump because kexec set the efi map
> > size to align with 16 when loading crash kernel image:
> >
> > in bzImage64_load()
> > efi_map_sz = efi_get_runtime_map_size();
> > efi_map_sz = ALIGN(efi_map_sz, 16);
> >
> > This patch changes the logic in the unmapping function. Using the
> > end address of map to calcuate original size.
> >
> > Thank Randy Wright for his report and testing. And also thank
> > Takashi Iwai for his help to trace issue.
>
> Good catch. The kexec code need to be fixed to use a separate buffer so
> avoid the alignment like what kexec-tools did. I can submit a fix for
> that.

Can you try below code, see if it works?

diff --git a/arch/x86/kernel/kexec-bzimage64.c b/arch/x86/kernel/kexec-bzimage64.c
index 3182908b7e6c..eaee37c54b7b 100644
--- a/arch/x86/kernel/kexec-bzimage64.c
+++ b/arch/x86/kernel/kexec-bzimage64.c
@@ -398,11 +398,10 @@ static void *bzImage64_load(struct kimage *image, char *kernel,
* little bit simple
*/
efi_map_sz = efi_get_runtime_map_size();
- efi_map_sz = ALIGN(efi_map_sz, 16);
params_cmdline_sz = sizeof(struct boot_params) + cmdline_len +
MAX_ELFCOREHDR_STR_LEN;
params_cmdline_sz = ALIGN(params_cmdline_sz, 16);
- kbuf.bufsz = params_cmdline_sz + efi_map_sz +
+ kbuf.bufsz = params_cmdline_sz + ALIGN(efi_map_sz, 16)+
sizeof(struct setup_data) +
sizeof(struct efi_setup_data);

@@ -410,7 +409,7 @@ static void *bzImage64_load(struct kimage *image, char *kernel,
if (!params)
return ERR_PTR(-ENOMEM);
efi_map_offset = params_cmdline_sz;
- efi_setup_data_offset = efi_map_offset + efi_map_sz;
+ efi_setup_data_offset = efi_map_offset + ALIGN(efi_map_sz, 16);

/* Copy setup header onto bootparams. Documentation/x86/boot.txt */
setup_header_size = 0x0202 + kernel[0x0201] - setup_hdr_offset;