Hello Vlastimil, On 12/7/2023 10:20 AM, Vlastimil Babka wrote:
+ +void snp_leak_pages(u64 pfn, unsigned int npages) +{ + struct page *page = pfn_to_page(pfn); + + pr_debug("%s: leaking PFN range 0x%llx-0x%llx\n", __func__, pfn, pfn + npages); + + spin_lock(&snp_leaked_pages_list_lock); + while (npages--) { + /* + * Reuse the page's buddy list for chaining into the leaked + * pages list. This page should not be on a free list currently + * and is also unsafe to be added to a free list. + */ + list_add_tail(&page->buddy_list, &snp_leaked_pages_list); + sev_dump_rmpentry(pfn); + pfn++;You increment pfn, but not page, which is always pointing to the page of the initial pfn, so need to do page++ too.
Yes, that is a bug and needs to be fixed.
But that assumes it's all order-0 pages (hard to tell for me whether that's true as we start with a pfn), if there can be compound pages, it would be best to only add the head page and skip the tail pages - it's not expected to use page->buddy_list of tail pages.
Can't we use PageCompound() to check if the page is a compound page and then use page->compound_head to get and add the head page to leaked pages list. I understand the tail pages for compound pages are really limited for usage.
Thanks, Ashish
