| Message ID | 20210830094232.203029-1-lizhijian@cn.fujitsu.com (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
| Series | [v3] mm/hmm: bypass devmap pte when all pfn requested flags are fulfilled | expand |
Looks good,
Reviewed-by: Christoph Hellwig <hch@lst.de>
On Mon, Aug 30, 2021 at 05:42:32PM +0800, Li Zhijian wrote: > Previously, we noticed the one rpma example was failed[1] since 36f30e486d, > where it will use ODP feature to do RDMA WRITE between fsdax files. > > After digging into the code, we found hmm_vma_handle_pte() will still > return EFAULT even though all the its requesting flags has been > fulfilled. That's because a DAX page will be marked as > (_PAGE_SPECIAL | PAGE_DEVMAP) by pte_mkdevmap(). > > [1]: https://github.com/pmem/rpma/issues/1142 > > CC: stable@vger.kernel.org > Fixes: 405506274922 ("mm/hmm: add missing call to hmm_pte_need_fault in HMM_PFN_SPECIAL handling") > Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com> > > --- > V3: adjust the checking order > --- > mm/hmm.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Andrew, can you grab this please? Thanks, Jason
diff --git a/mm/hmm.c b/mm/hmm.c index fad6be2bf072..842e26599238 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -295,10 +295,13 @@ static int hmm_vma_handle_pte(struct mm_walk *walk, unsigned long addr, goto fault; /* + * Bypass devmap pte such as DAX page when all pfn requested + * flags(pfn_req_flags) are fulfilled. * Since each architecture defines a struct page for the zero page, just * fall through and treat it like a normal page. */ - if (pte_special(pte) && !is_zero_pfn(pte_pfn(pte))) { + if (pte_special(pte) && !pte_devmap(pte) && + !is_zero_pfn(pte_pfn(pte))) { if (hmm_pte_need_fault(hmm_vma_walk, pfn_req_flags, 0)) { pte_unmap(ptep); return -EFAULT;
Previously, we noticed the one rpma example was failed[1] since 36f30e486d, where it will use ODP feature to do RDMA WRITE between fsdax files. After digging into the code, we found hmm_vma_handle_pte() will still return EFAULT even though all the its requesting flags has been fulfilled. That's because a DAX page will be marked as (_PAGE_SPECIAL | PAGE_DEVMAP) by pte_mkdevmap(). [1]: https://github.com/pmem/rpma/issues/1142 CC: stable@vger.kernel.org Fixes: 405506274922 ("mm/hmm: add missing call to hmm_pte_need_fault in HMM_PFN_SPECIAL handling") Signed-off-by: Li Zhijian <lizhijian@cn.fujitsu.com> --- V3: adjust the checking order --- mm/hmm.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)