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 hsYCJBb9 DuVNo27DoU/pr2NbF4kRqzwCnSBqKVKWHaZvhba5W+nzBdNDIRSCRymUuEuLHtzNplMf2oqd0FUq8r/lxz+V3E3Ui6wUXKfIMtJMx5zzHCAlusBkBjXLCoLy6uGYQU6988uhdAaqcC2ma7WUSQ3IUA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jun 11, 2025 at 10:42:16AM +0200, Marek Szyprowski wrote: > On 11.06.2025 10:23, David Hildenbrand wrote: > > On 11.06.25 10:03, Marek Szyprowski wrote: > >> On 11.06.2025 04:38, Alistair Popple wrote: > >>> On Tue, Jun 10, 2025 at 06:18:09PM +0200, Marek Szyprowski wrote: > >>>> On 04.06.2025 05:21, Alistair Popple wrote: > >>>>> The PFN_MAP flag is no longer used for anything, so remove it. > >>>>> The PFN_SG_CHAIN and PFN_SG_LAST flags never appear to have been > >>>>> used so also remove them. The last user of PFN_SPECIAL was removed > >>>>> by 653d7825c149 ("dcssblk: mark DAX broken, remove FS_DAX_LIMITED > >>>>> support"). > >>>>> > >>>>> Signed-off-by: Alistair Popple > >>>>> Acked-by: David Hildenbrand > >>>>> Reviewed-by: Christoph Hellwig > >>>>> Reviewed-by: Jason Gunthorpe > >>>>> Cc: gerald.schaefer@linux.ibm.com > >>>>> Cc: dan.j.williams@intel.com > >>>>> Cc: jgg@ziepe.ca > >>>>> Cc: willy@infradead.org > >>>>> Cc: david@redhat.com > >>>>> Cc: linux-kernel@vger.kernel.org > >>>>> Cc: nvdimm@lists.linux.dev > >>>>> Cc: jhubbard@nvidia.com > >>>>> Cc: hch@lst.de > >>>>> Cc: zhang.lyra@gmail.com > >>>>> Cc: debug@rivosinc.com > >>>>> Cc: bjorn@kernel.org > >>>>> Cc: balbirs@nvidia.com > >>>>> Cc: lorenzo.stoakes@oracle.com > >>>>> Cc: John@Groves.net > >>>>> > >>>>> --- > >>>>> > >>>>> Splitting this off from the rest of my series[1] as a separate > >>>>> clean-up > >>>>> for consideration for the v6.16 merge window as suggested by > >>>>> Christoph. > >>>>> > >>>>> [1] - > >>>>> https://lore.kernel.org/linux-mm/cover.541c2702181b7461b84f1a6967a3f0e823023fcc.1748500293.git-series.apopple@nvidia.com/ > >>>>> --- > >>>>>     include/linux/pfn_t.h             | 31 > >>>>> +++---------------------------- > >>>>>     mm/memory.c                       |  2 -- > >>>>>     tools/testing/nvdimm/test/iomap.c |  4 ---- > >>>>>     3 files changed, 3 insertions(+), 34 deletions(-) > >>>> This patch landed in today's linux-next as commit 28be5676b4a3 ("mm: > >>>> remove PFN_MAP, PFN_SPECIAL, PFN_SG_CHAIN and PFN_SG_LAST"). In my > >>>> tests > >>>> I've noticed that it breaks operation of all RISC-V 64bit boards on my > >>>> test farm (VisionFive2, BananaPiF3 as well as QEMU's Virt machine). > >>>> I've > >>>> isolated the changes responsible for this issue, see the inline > >>>> comments > >>>> in the patch below. Here is an example of the issues observed in the > >>>> logs from those machines: > >>> Thanks for the report. I'm really confused by this because this > >>> change should > >>> just be removal of dead code - nothing sets any of the removed PFN_* > >>> flags > >>> AFAICT. > >>> > >>> I don't have access to any RISC-V hardwdare but you say this > >>> reproduces under > >>> qemu - what do you run on the system to cause the error? Is it just > >>> a simple > >>> boot and load a module or are you running selftests or something else? > >> > >> It fails a simple boot test. Here is a detailed instruction how to > >> reproduce this issue with the random Debian rootfs image found on the > >> internet (tested on Ubuntu 22.04, with next-20250610 > >> kernel source): > > > > riscv is one of the archs where pte_mkdevmap() will *not* set the pte > > as special. (I > > raised this recently in the original series, it's all a big mess) > > > > So, before this change here, pfn_t_devmap() would have returned > > "false" if only > > PFN_DEV was set, now it would return "true" if only PFN_DEV is set. Ugh, what a mess. Thanks for pointing that out (I had seen your earlier response to the original series but hadn't found the time to look into it more deeply). > > Consequently, in insert_pfn() we would have done a pte_mkspecial(), > > now we do a > > pte_mkdevmap() -- again, which does not imply "special" on riscv. > > > > riscv selects CONFIG_ARCH_HAS_PTE_SPECIAL, so if !pte_special(), it's > > considered as > > normal. > > > > Would the following fix your issue? > > > > > > diff --git a/mm/memory.c b/mm/memory.c > > index 8eba595056fe3..0e972c3493692 100644 > > --- a/mm/memory.c > > +++ b/mm/memory.c > > @@ -589,6 +589,10 @@ struct page *vm_normal_page(struct vm_area_struct > > *vma, unsigned long addr, > >  { > >         unsigned long pfn = pte_pfn(pte); > > > > +       /* TODO: remove this crap and set pte_special() instead. */ > > +       if (pte_devmap(pte)) > > +               return NULL; > > + > >         if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) { > >                 if (likely(!pte_special(pte))) > >                         goto check_pfn; > > @@ -598,16 +602,6 @@ struct page *vm_normal_page(struct vm_area_struct > > *vma, unsigned long addr, > >                         return NULL; > >                 if (is_zero_pfn(pfn)) > >                         return NULL; > > -               if (pte_devmap(pte)) > > -               /* > > -                * NOTE: New users of ZONE_DEVICE will not set > > pte_devmap() > > -                * and will have refcounts incremented on their struct > > pages > > -                * when they are inserted into PTEs, thus they are > > safe to > > -                * return here. Legacy ZONE_DEVICE pages that set > > pte_devmap() > > -                * do not have refcounts. Example of legacy > > ZONE_DEVICE is > > -                * MEMORY_DEVICE_FS_DAX type in pmem or virtio_fs > > drivers. > > -                */ > > -                       return NULL; > > > >                 print_bad_pte(vma, addr, pte, NULL); > >                 return NULL; > > > > > > But, I would have thought the later patches in Alistairs series would > > sort that out > > (where we remove pte_devmap() ... ) > > Yes, I think Marek confirmed that it did in his earlier reply. > The above change fixes the issues observed on RISCV boards. Thanks for testing. Andrew has already removed this from the -mm tree so I'll reincorporate this back into the series and see if I can figure something out when I respin it. - Alistair > Best regards > -- > Marek Szyprowski, PhD > Samsung R&D Institute Poland >