On Mon, Apr 27, 2026 at 08:33:30PM +0800, Lance Yang wrote: > >On Fri, Apr 24, 2026 at 05:23:59AM -0700, Breno Leitao wrote: >>When get_hwpoison_page() returns a negative value, distinguish >>reserved pages from other failure cases by reporting MF_MSG_KERNEL >>instead of MF_MSG_GET_HWPOISON. Reserved pages belong to the kernel >>and should be classified accordingly for proper handling. >> >>Acked-by: Miaohe Lin <[email protected]> >>Signed-off-by: Breno Leitao <[email protected]> >>--- >> mm/memory-failure.c | 11 ++++++++++- >> 1 file changed, 10 insertions(+), 1 deletion(-) >> >>diff --git a/mm/memory-failure.c b/mm/memory-failure.c >>index ee42d43613097..7b67e43dafbd1 100644 >>--- a/mm/memory-failure.c >>+++ b/mm/memory-failure.c >>@@ -2432,7 +2432,16 @@ int memory_failure(unsigned long pfn, int flags) >> } >> goto unlock_mutex; >> } else if (res < 0) { >>- res = action_result(pfn, MF_MSG_GET_HWPOISON, MF_IGNORED); >>+ /* >>+ * PageReserved is stable here: reserved pages have >>+ * PG_reserved set at boot or by drivers and are never >>+ * freed through the page allocator. >>+ */ > >Not necessarily. PG_reserved is not a permanent lifetime property for >every page that has carried it. > >page-flags.h says early reserved pages may later have PG_reserved >cleared and then be given to the page allocator :) > >At least some drivers also clear PG_reserved when releasing pages they >marked reserved. > >Would it be clearer to say that pages with PG_reserved set are not >currently managed by the page allocator, rather than saying reserved >pages are never freed through the page allocator? > >Otherwise, LGTM.
Ouch, I missed one more thing ... Sashiko pointed out that[1] > + if (PageReserved(p)) "Can this introduce a use-after-free risk on the struct page?" get_any_page() may put the page before returning -EIO. After that ref is dropped, PageReserved(p) is not safe, IIUC :( Maybe just cache it before the call? is_reserved = PageReserved(p); res = get_hwpoison_page(p, flags); [1] https://sashiko.dev/#/patchset/[email protected]
