> -----Original Message----- > From: Miaohe Lin <linmiaohe@xxxxxxxxxx> > Sent: Friday, August 12, 2022 09:59 > To: Wang, Haiyue <haiyue.wang@xxxxxxxxx> > Cc: akpm@xxxxxxxxxxxxxxxxxxxx; Linux-MM <linux-mm@xxxxxxxxx>; linux-kernel <linux- > kernel@xxxxxxxxxxxxxxx>; Naoya Horiguchi <naoya.horiguchi@xxxxxxxxx>; David Hildenbrand > <david@xxxxxxxxxx> > Subject: Re: Linux 5.19 __NR_move_pages failed for hugepage > > On 2022/8/11 16:01, Wang, Haiyue wrote: > > Hi Miaohe, > > > > > > Hi Haiyue, > > Many thanks for your report and debug. > > > > > When I call "*syscall (__NR_move_pages, 0, n_pages, ptr, 0, status, 0)*" to get the huge page node > > > > information, it is failed with '-2' returned in 'status' array. > > > > > > > > After some debug, I found that "*follow_huge_pud*" will return NULL if '*FOLL_GET*' is set. > > > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e66f17ff71772b209eed39de > 35aaa99ba819c93d > <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e66f17ff71772b209eed39d > e35aaa99ba819c93d> > > > > > > > > This will make your patch doesn't work for huge page. > > > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4cd614841c06338a087769ee > 3cfa96718784d1f5 > <https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=4cd614841c06338a087769e > e3cfa96718784d1f5> > > > > Supporting of '*FOLL_GET*' in follow_huge_pud is introduced via the below commit: > > https://lore.kernel.org/all/20220714042420.1847125-9- > naoya.horiguchi@xxxxxxxxx/T/#mb3c83df087fba454b7b4ea32227fb8775ca70081 > > But that's still not perfect yet. For s390 version of follow_huge_pud, FOLL_GET is still not supported. > And pgd level > hugepage doesn't support FOLL_GET now. > > > > > > > Not sure you know this issue or not, just share my debug information. > > I'm not sure whether it's better to revert my above "problematic" patch first then add it back when > all hugetlb pages support FOLL_GET. > Or we could just live with it? Any thoughts? > TBH, the issue is more complicated than I think. :-( Looks like only '[PATCH v7 5/8] mm, hwpoison: set PG_hwpoison for busy hugetlb pages' will be backported to 5.19 ? Only this patch has "Fixes:" tag. If so, it will break 5.19. I just run VPP 'https://fd.io/' to find the error message about huge page allocation after I switched from 5.18 to 5.19. > > Thanks, > Miaohe Lin > > > > > > > > > > BR, > > > > Haiyue > > > > > >
