On 21.11.23 14:21, Sumanth Korikkar wrote:
On Tue, Nov 21, 2023 at 02:13:22PM +0100, Sumanth Korikkar wrote:Approach 2: =========== Shouldnt kasan zero shadow mapping performed first before accessing/initializing memmap via page_init_poisining()? If that is true, then it is a problem for all architectures and should could be fixed like: diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 7a5fc89a8652..eb3975740537 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1093,6 +1093,7 @@ int mhp_init_memmap_on_memory(unsigned long pfn, unsigned long nr_pages, if (ret) return ret; + page_init_poison(pfn_to_page(pfn), sizeof(struct page) * nr_pages); move_pfn_range_to_zone(zone, pfn, nr_pages, NULL, MIGRATE_UNMOVABLE); for (i = 0; i < nr_pages; i++) diff --git a/mm/sparse.c b/mm/sparse.c index 77d91e565045..4ddf53f52075 100644 --- a/mm/sparse.c +++ b/mm/sparse.c @@ -906,8 +906,11 @@ int __meminit sparse_add_section(int nid, unsigned long start_pfn, /* * Poison uninitialized struct pages in order to catch invalid flags * combinations. + * For altmap, do this later when onlining the memory, as it might + * not be accessible at this point. */ - page_init_poison(memmap, sizeof(struct page) * nr_pages); + if (!altmap) + page_init_poison(memmap, sizeof(struct page) * nr_pages); ms = __nr_to_section(section_nr); set_section_nid(section_nr, nid); Also, if this approach is taken, should page_init_poison() be performed with cond_resched() as mentioned in commit d33695b16a9f ("mm/memory_hotplug: poison memmap in remove_pfn_range_from_zone()") ?Sorry, wrong commit id. should page_init_poison() be performed with cond_resched() as mentioned in Commit b7e3debdd040 ("mm/memory_hotplug.c: fix false softlockup during pfn range removal") ?
I think people are currently looking into removing all that cond_resched(): https://lore.kernel.org/all/20231107230822.371443-29-ankur.a.arora@xxxxxxxxxx/T/#mda52da685a142bec9607625386b0b660e5470abe -- Cheers, David / dhildenb
