Re: [RESEND PATCH v5 06/11] ppc64/kexec_file: restrict memory usage of kdump kernel

[Hari Bathini]

On 28/07/20 7:14 pm, Michael Ellerman wrote:
> Hari Bathini <hbathini@xxxxxxxxxxxxx> writes:
> > diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c
> > index 2df6f4273ddd..8df085a22fd7 100644
> > --- a/arch/powerpc/kexec/file_load_64.c
> > +++ b/arch/powerpc/kexec/file_load_64.c
> > @@ -17,9 +17,21 @@
> >   #include <linux/kexec.h>
> >   #include <linux/of_fdt.h>
> >   #include <linux/libfdt.h>
> > +#include <linux/of_device.h>
> >   #include <linux/memblock.h>
> > +#include <linux/slab.h>
> > +#include <asm/drmem.h>
> >   #include <asm/kexec_ranges.h>
> >   
> > +struct umem_info {
> > +	uint64_t *buf; /* data buffer for usable-memory property */
> > +	uint32_t idx;  /* current index */
> > +	uint32_t size; /* size allocated for the data buffer */
>
> Use kernel types please, u64, u32.
>
> > +	/* usable memory ranges to look up */
> > +	const struct crash_mem *umrngs;
>
> "umrngs".
>
> Given it's part of the umem_info struct could it just be "ranges"?

True. Actually, having crash_mem_range *ranges + u32 nr_ranges and 
populating them seems better. Will do that..

> > +		return NULL;
> > +	}
>
> 	um_info->size = new_size;
>
> > +
> > +	memset(tbuf + um_info->idx, 0, MEM_RANGE_CHUNK_SZ);
>
> Just pass __GFP_ZERO to krealloc?

There are patches submitted to stable fixing a few modules that use 
krealloc with __GFP_ZERO. Also, this zeroing is not really needed.
I will drop the memset instead..

Thanks
Hari