On 2025/2/25 5:14, Jane Chu wrote: > When a process consumes a UE in a page, the memory failure handler > attempts to collect information for a potential SIGBUS. > If the page is an anonymous page, page_mapped_in_vma(page, vma) is > invoked in order to > 1. retrieve the vaddr from the process' address space, > 2. verify that the vaddr is indeed mapped to the poisoned page, > where 'page' is the precise small page with UE. > > It's been observed that when injecting poison to a non-head subpage > of an anonymous hugetlb page, no SIGBUS show up; while injecting to > the head page produces a SIGBUS. The casue is that, though hugetlb_walk() > returns a valid pmd entry (on x86), but check_pte() detects mismatch > between the head page per the pmd and the input subpage. Thus the vaddr > is considered not mapped to the subpage and the process is not collected > for SIGBUS purpose. This is the calling stack > collect_procs_anon > page_mapped_in_vma > page_vma_mapped_walk > hugetlb_walk > huge_pte_lock > check_pte > > check_pte() header says that it > "check if [pvmw->pfn, @pvmw->pfn + @pvmw->nr_pages) is mapped at the @pvmw->pte" > but practically works only if pvmw->pfn is the head page pfn at pvmw->pte. > Hindsight acknowledging that some pvmw->pte could point to a hugepage of > some sort such that it makes sense to make check_pte() work for hugepage. Thanks for your patch. This patch looks good to me. > > Signed-off-by: Jane Chu <jane.chu@xxxxxxxxxx> Is a Fixes tag needed? Thanks. .
