On Fri, Jun 28, 2019 at 12:51:19AM +0530, Hari Bathini wrote:
> Currently, if memory_limit is specified and it overlaps with memory to
> be reserved for capture kernel, memory_limit is adjusted to accommodate
> capture kernel. With memory reservation for capture kernel moved later
> (after enforcing memory limit), this adjustment no longer holds water.
> So, avoid adjusting memory_limit and error out instead.
The adjustment of memory limit does not look quite sound
- There is no code to undo the adjustment in case reservation fails
- I don't think reservation is still forced to the end of memory
causing the kernel to use memory it was supposed not to
- The CMA reservation again causes teh reserved memory to be used
- Finally the CMA reservation makes this obsolete because the reserved
memory is can be used by the system
>
> Signed-off-by: Hari Bathini <hbath...@linux.ibm.com>
Reviewed-by: Michal Suchanek <msucha...@suse.de>
> ---
> arch/powerpc/kernel/fadump.c | 16 ----------------
> arch/powerpc/kernel/machine_kexec.c | 22 +++++++++++-----------
> 2 files changed, 11 insertions(+), 27 deletions(-)
>
> diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c
> index 4eab972..a784695 100644
> --- a/arch/powerpc/kernel/fadump.c
> +++ b/arch/powerpc/kernel/fadump.c
> @@ -476,22 +476,6 @@ int __init fadump_reserve_mem(void)
> #endif
> }
>
> - /*
> - * Calculate the memory boundary.
> - * If memory_limit is less than actual memory boundary then reserve
> - * the memory for fadump beyond the memory_limit and adjust the
> - * memory_limit accordingly, so that the running kernel can run with
> - * specified memory_limit.
> - */
> - if (memory_limit && memory_limit < memblock_end_of_DRAM()) {
> - size = get_fadump_area_size();
> - if ((memory_limit + size) < memblock_end_of_DRAM())
> - memory_limit += size;
> - else
> - memory_limit = memblock_end_of_DRAM();
> - printk(KERN_INFO "Adjusted memory_limit for firmware-assisted"
> - " dump, now %#016llx\n", memory_limit);
> - }
> if (memory_limit)
> memory_boundary = memory_limit;
> else
> diff --git a/arch/powerpc/kernel/machine_kexec.c
> b/arch/powerpc/kernel/machine_kexec.c
> index c4ed328..fc5533b 100644
> --- a/arch/powerpc/kernel/machine_kexec.c
> +++ b/arch/powerpc/kernel/machine_kexec.c
> @@ -125,10 +125,8 @@ void __init reserve_crashkernel(void)
> crashk_res.end = crash_base + crash_size - 1;
> }
>
> - if (crashk_res.end == crashk_res.start) {
> - crashk_res.start = crashk_res.end = 0;
> - return;
> - }
> + if (crashk_res.end == crashk_res.start)
> + goto error_out;
>
> /* We might have got these values via the command line or the
> * device tree, either way sanitise them now. */
> @@ -170,15 +168,13 @@ void __init reserve_crashkernel(void)
> if (overlaps_crashkernel(__pa(_stext), _end - _stext)) {
> printk(KERN_WARNING
> "Crash kernel can not overlap current kernel\n");
> - crashk_res.start = crashk_res.end = 0;
> - return;
> + goto error_out;
> }
>
> /* Crash kernel trumps memory limit */
> if (memory_limit && memory_limit <= crashk_res.end) {
> - memory_limit = crashk_res.end + 1;
> - printk("Adjusted memory limit for crashkernel, now 0x%llx\n",
> - memory_limit);
> + pr_err("Crash kernel size can't exceed memory_limit\n");
> + goto error_out;
> }
>
> printk(KERN_INFO "Reserving %ldMB of memory at %ldMB "
> @@ -190,9 +186,13 @@ void __init reserve_crashkernel(void)
> if (!memblock_is_region_memory(crashk_res.start, crash_size) ||
> memblock_reserve(crashk_res.start, crash_size)) {
> pr_err("Failed to reserve memory for crashkernel!\n");
> - crashk_res.start = crashk_res.end = 0;
> - return;
> + goto error_out;
> }
> +
> + return;
> +error_out:
> + crashk_res.start = crashk_res.end = 0;
> + return;
> }
>
> int overlaps_crashkernel(unsigned long start, unsigned long size)
>
