On Tue, Jun 07, 2022 at 03:04:15PM +0200, David Hildenbrand wrote: > On 02.06.22 07:06, Naoya Horiguchi wrote: > > From: Naoya Horiguchi <naoya.horiguchi@xxxxxxx> > > > > When handling memory error on a hugetlb page, the error handler tries to > > dissolve and turn it into 4kB pages. If it's successfully dissolved, > > PageHWPoison flag is moved to the raw error page, so that's all right. > > However, dissolve sometimes fails, then the error page is left as > > hwpoisoned hugepage. It's useful if we can retry to dissolve it to save > > healthy pages, but that's not possible now because the information about > > where the raw error page is lost. > > > > Use the private field of a tail page to keep that information. The code > > path of shrinking hugepage pool used this info to try delayed dissolve. > > This only keeps one hwpoison page for now, which might be OK because it's > > simple and multiple hwpoison pages in a hugepage can be rare. But it can > > be extended in the future. > > > > > > But what would happen now if you have multiple successive MCE events on > such a page now? The 2nd and later events are ignored due to "already hwpoisoned hugepage", this might not be good when the hwpoisoned hugepage is freed/dissolved later. So a temporal workaround is to remember "hugepage has multiple hwpoison pages" and disable free/dissolve for such hugepages. Thanks, Naoya Horiguchi
