On 05/05/20 3:29 am, Eric W. Biederman wrote: > > Recently a patch was proposed to kimage_alloc_page to slightly alter > the logic of how pages allocated with incompatible flags were > detected. The logic was being altered because the semantics of the > page alloctor were changing yet again. > > Looking at that case I realized that there is no reason for it to even > exist. Either the indirect page allocations and the source page > allocations could be separated out, or I could do as I am doing now > and simply teach the indirect pages to live in high memory. > > This patch replaced pointers of type kimage_entry_t * with a new type > kimage_entry_pos_t. This new type holds the physical address of the > indirect page and the offset within that page of the next indirect > entry to write. A special constant KIMAGE_ENTRY_POS_INVALID is added > that kimage_image_pos_t variables that don't currently have a valid > may be set to. > > Two new functions kimage_read_entry and kimage_write_entry have been > provided to write entries in way that works if they live in high > memory. > > The now unnecessary checks to see if a destination entry is non-zero > and to increment it if so have been removed. For safety new indrect > pages are now cleared so we have a guarantee everything that has not > been used yet is zero. Along with this writing an extra trailing 0 > entry has been removed, as it is known all trailing entries are now 0. > > With highmem support implemented for indirect pages > kimage_image_alloc_page has been updated to always allocate > GFP_HIGHUSER pages, and handling of pages with different > gfp flags has been removed. > > Signed-off-by: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx> Eric, the patch failed with data access exception on ppc64. Using the below patch on top got me going... diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c index 45862fd..bef52f1 100644 --- a/kernel/kexec_core.c +++ b/kernel/kexec_core.c @@ -570,7 +570,12 @@ static int kimage_add_entry(struct kimage *image, kimage_entry_t entry) return -ENOMEM; ind_addr = page_to_boot_pfn(page) << PAGE_SHIFT; - kimage_write_entry(image->entry_pos, ind_addr | IND_INDIRECTION); + + /* If it is the first entry, handle it here */ + if (!image->head) + image->head = ind_addr | IND_INDIRECTION; + else + kimage_write_entry(image->entry_pos, ind_addr | IND_INDIRECTION); clear_highpage(page); @@ -623,7 +628,11 @@ int __weak machine_kexec_post_load(struct kimage *image) void kimage_terminate(struct kimage *image) { - kimage_write_entry(image->entry_pos, IND_DONE); + /* This could be the only entry in case of kdump */ + if (!image->head) + image->head = IND_DONE; + else + kimage_write_entry(image->entry_pos, IND_DONE); } #define for_each_kimage_entry(image, pos, entry) \ Thanks Hari _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec