On 06/19/2019 09:47 AM, Anshuman Khandual wrote: > +#ifdef CONFIG_MEMORY_HOTPLUG > + /* > + * FIXME: We should have called remove_pagetable(start, end, true). > + * vmemmap and vmalloc virtual range might share intermediate kernel > + * page table entries. Removing vmemmap range page table pages here > + * can potentially conflict with a cuncurrent vmalloc() allocation. > + * > + * This is primarily because valloc() does not take init_mm ptl for > + * the entire page table walk and it's modification. Instead it just > + * takes the lock while allocating and installing page table pages > + * via [p4d|pud|pmd|pte]_aloc(). A cuncurrently vanishing page table > + * entry via memory hotremove can cause vmalloc() kernel page table > + * walk pointers to be invalid on the fly which can cause corruption > + * or worst, a crash. There are couple of typos above which I will fix along with other reviews.
