Hi,
On Thu, 21 Mar 2024 at 05:56, Huang, Kai <kai.huang@xxxxxxxxx> wrote:
>
> Hi Dave,
>
> Some nitpicking in changelog:
Will fix the grammar issues. Thanks for your review!
>
> On 5/03/2024 2:32 pm, Dave Young wrote:
> > crashkernel reservation failed on a Thinkpad t440s laptop recently,
>
> ',' -> '.' to make it as a standalone sentence.
>
> > Actually the memblock reservation succeeded, but later insert_resource()
> > failed.
> >
> > Test step:
> > kexec load ->
> > kexec reboot ->
> > check the crashkernel memory
> > dmesg|grep "crashkernel reserved"; saw reserved suceeeded:
>
> "suceeeded" -> "succeeded".
>
> > 0x00000000d0000000 - 0x00000000da000000
> > grep Crash /proc/iomem: got nothing
>
> And somehow I found it's not easy to read. :-)
>
> >
> > The background story is like below:
>
> Better to have an blank line to make text more breathable.
>
> > Currently E820 code reserves setup_data regions for both the current kernel
> > and the kexec kernel, and it will also insert them into resources list.
>
> "will insert" -> "inserts".
>
> > Before the kexec kernel reboot nobody passes the old setup_data, kexec only
>
> ^ "reboots" ^ and
>
> > passes SETUP_EFI and SETUP_IMA if needed. Thus the old setup data memory
> > are not used at all. But due to old kernel updated the kexec e820 table
>
> ^ is ^ updates
>
> > as well so kexec kernel see them as E820_TYPE_RESERVED_KERN regions, later
>
> "so kexec kernel" -> ", the kexec kernel"
>
> "see" -> "sees"
>
> ", later" -> ", and later"
>
> > the old setup_data regions will be inserted into resources list in kexec
>
> "will be" -> "are"
>
> > kernel by e820__reserve_resources().
> >
> > Note, due to no setup_data passed in for those old regions they are not
>
> ^ is
>
> > early reserved (by function early_reserve_memory), crashkernel memblock
>
> ^ and the
>
> > reservation will just regard them as usable memory and it could reserve
>
> "regard" -> "treat"
>
> > reserve crashkernel region overlaps with the old setup_data regions.
>
> double "reserve".
>
> "crashkernel region" -> "the crashkernel region"
>
> "overlaps" -> "which overlaps"
>
> >
> > Just like the bug I noticed here, kdump insert_resource failed because
> > e820__reserve_resources added the overlapped chunks in /proc/iomem already.
>
> ^ has added
> >
> > Finally, looking at the code, the old setup_data regions are not used
> > at all as no setup_data passed in by the kexec boot loader. Although
>
> ^ is passed
>
> > something like SETUP_PCI etc could be needed, kexec should pass
> > the info as setup_data so that kexec kernel can take care of them.
> > This should be taken care of in other separate patches if needed.
> >
> > Thus drop the useless buggy code here.
> >
> > Signed-off-by: Dave Young <dyoung@xxxxxxxxxx>
> > ---
> > arch/x86/kernel/e820.c | 16 +---------------
> > 1 file changed, 1 insertion(+), 15 deletions(-)
> >
> > Index: linux/arch/x86/kernel/e820.c
> > ===================================================================
> > --- linux.orig/arch/x86/kernel/e820.c
> > +++ linux/arch/x86/kernel/e820.c
> > @@ -1015,16 +1015,6 @@ void __init e820__reserve_setup_data(voi
> > pa_next = data->next;
> >
> > e820__range_update(pa_data, sizeof(*data)+data->len, E820_TYPE_RAM, E820_TYPE_RESERVED_KERN);
> > -
> > - /*
> > - * SETUP_EFI and SETUP_IMA are supplied by kexec and do not need
> > - * to be reserved.
> > - */
> > - if (data->type != SETUP_EFI && data->type != SETUP_IMA)
> > - e820__range_update_kexec(pa_data,
> > - sizeof(*data) + data->len,
> > - E820_TYPE_RAM, E820_TYPE_RESERVED_KERN);
> > -
> > if (data->type == SETUP_INDIRECT) {
> > len += data->len;
> > early_memunmap(data, sizeof(*data));
> > @@ -1036,12 +1026,9 @@ void __init e820__reserve_setup_data(voi
> >
> > indirect = (struct setup_indirect *)data->data;
> >
> > - if (indirect->type != SETUP_INDIRECT) {
> > + if (indirect->type != SETUP_INDIRECT)
> > e820__range_update(indirect->addr, indirect->len,
> > E820_TYPE_RAM, E820_TYPE_RESERVED_KERN);
> > - e820__range_update_kexec(indirect->addr, indirect->len,
> > - E820_TYPE_RAM, E820_TYPE_RESERVED_KERN);
> > - }
> > }
> >
> > pa_data = pa_next;
> > @@ -1049,7 +1036,6 @@ void __init e820__reserve_setup_data(voi
> > }
> >
> > e820__update_table(e820_table);
> > - e820__update_table(e820_table_kexec);
> >
> > pr_info("extended physical RAM map:\n");
> > e820__print_table("reserve setup_data");
> >
> >
>
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