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* mm/hmm: return error for non-vma snapshotsJason Gunthorpe2020-03-301-3/+5
| | | | | | | | | | | | | | | The pagewalker does not call most ops with NULL vma, those are all routed to hmm_vma_walk_hole() via ops->pte_hole instead. Thus hmm_vma_fault() is only called with a NULL vma from hmm_vma_walk_hole(), so hoist the NULL vma check to there. Now it is clear that snapshotting with no vma is a HMM_PFN_ERROR as without a vma we have no path to call hmm_vma_fault(). Link: https://lore.kernel.org/r/20200327200021.29372-10-jgg@ziepe.ca Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: do not set pfns when returning an error codeJason Gunthorpe2020-03-301-15/+3
| | | | | | | | | | | | | | | | | | Most places that return an error code, like -EFAULT, do not set HMM_PFN_ERROR, only two places do this. Resolve this inconsistency by never setting the pfns on an error exit. This doesn't seem like a worthwhile thing to do anyhow. If for some reason it becomes important, it makes more sense to directly return the address of the failing page rather than have the caller scan for the HMM_PFN_ERROR. No caller inspects the pnfs output array if hmm_range_fault() fails. Link: https://lore.kernel.org/r/20200327200021.29372-9-jgg@ziepe.ca Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: do not unconditionally set pfns when returning EBUSYJason Gunthorpe2020-03-301-3/+4
| | | | | | | | | | | | | | | | | In hmm_vma_handle_pte() and hmm_vma_walk_hugetlb_entry() if fault happens then -EBUSY will be returned and the pfns input flags will have been destroyed. For hmm_vma_handle_pte() set HMM_PFN_NONE only on the success returns that don't otherwise store to pfns. For hmm_vma_walk_hugetlb_entry() all exit paths already set pfns, so remove the redundant store. Fixes: 2aee09d8c116 ("mm/hmm: change hmm_vma_fault() to allow write fault on page basis") Link: https://lore.kernel.org/r/20200327200021.29372-8-jgg@ziepe.ca Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: use device_private_entry_to_pfn()Jason Gunthorpe2020-03-301-1/+1
| | | | | | | | | | | | swp_offset() should not be called directly, the wrappers are supposed to abstract away the encoding of the device_private specific information in the swap entry. Link: https://lore.kernel.org/r/20200327200021.29372-7-jgg@ziepe.ca Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: Ralph Campbell <rcampbell@nvidia.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: remove HMM_FAULT_SNAPSHOTJason Gunthorpe2020-03-271-8/+9
| | | | | | | | | | | | | | | | | | | Now that flags are handled on a fine-grained per-page basis this global flag is redundant and has a confusing overlap with the pfn_flags_mask and default_flags. Normalize the HMM_FAULT_SNAPSHOT behavior into one place. Callers needing the SNAPSHOT behavior should set a pfn_flags_mask and default_flags that always results in a cleared HMM_PFN_VALID. Then no pages will be faulted, and HMM_FAULT_SNAPSHOT is not a special flow that overrides the masking mechanism. As this is the last flag, also remove the flags argument. If future flags are needed they can be part of the struct hmm_range function arguments. Link: https://lore.kernel.org/r/20200327200021.29372-5-jgg@ziepe.ca Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: remove unused code and tidy commentsJason Gunthorpe2020-03-271-7/+17
| | | | | | | | | | Delete several functions that are never called, fix some desync between comments and structure content, toss the now out of date top of file header, and move one function only used by hmm.c into hmm.c Link: https://lore.kernel.org/r/20200327200021.29372-4-jgg@ziepe.ca Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: return the fault type from hmm_pte_need_fault()Jason Gunthorpe2020-03-271-102/+81
| | | | | | | | | | | | Using two bools instead of flags return is not necessary and leads to bugs. Returning a value is easier for the compiler to check and easier to pass around the code flow. Convert the two bools into flags and push the change to all callers. Link: https://lore.kernel.org/r/20200327200021.29372-3-jgg@ziepe.ca Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: remove pgmap checking for devmap pagesJason Gunthorpe2020-03-271-48/+2
| | | | | | | | | | | | | The checking boils down to some racy check if the pagemap is still available or not. Instead of checking this, rely entirely on the notifiers, if a pagemap is destroyed then all pages that belong to it must be removed from the tables and the notifiers triggered. Link: https://lore.kernel.org/r/20200327200021.29372-2-jgg@ziepe.ca Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Tested-by: Ralph Campbell <rcampbell@nvidia.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: check the device private page owner in hmm_range_fault()Christoph Hellwig2020-03-261-1/+9
| | | | | | | | | | | | | | | | | | | | | hmm_range_fault() will succeed for any kind of device private memory, even if it doesn't belong to the calling entity. While nouveau has some crude checks for that, they are broken because they assume nouveau is the only user of device private memory. Fix this by passing in an expected pgmap owner in the hmm_range_fault structure. If a device_private page is found and doesn't match the owner then it is treated as an non-present and non-faultable page. This prevents a bug in amdgpu, where it doesn't know how to handle device_private pages, but hmm_range_fault would return them anyhow. Fixes: 4ef589dc9b10 ("mm/hmm/devmem: device memory hotplug using ZONE_DEVICE") Link: https://lore.kernel.org/r/20200316193216.920734-5-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm: simplify device private page handling in hmm_range_faultChristoph Hellwig2020-03-261-20/+5
| | | | | | | | | | | | | | Remove the HMM_PFN_DEVICE_PRIVATE flag, no driver has ever set this flag on input, and the only place that uses it on output can be trivially changed to use is_device_private_page(). This removes the ability to request that device_private pages are faulted back into system memory. Link: https://lore.kernel.org/r/20200316193216.920734-4-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm: merge hmm_vma_do_fault into into hmm_vma_walk_hole_Christoph Hellwig2020-03-261-34/+16
| | | | | | | | | There is no good reason for this split, as it just obsfucates the flow. Link: https://lore.kernel.org/r/20200316135310.899364-6-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: don't handle the non-fault case in hmm_vma_walk_hole_()Christoph Hellwig2020-03-261-19/+18
| | | | | | | | | | | | | | | | | | | Setting a pfns entry to NONE before returning -EBUSY is a bug that will cause corruption of the input flags on the next loop. There is just a single caller using hmm_vma_walk_hole_() for the non-fault case. Use hmm_pfns_fill() to fill the whole pfn array with zeroes in the only caller for the non-fault case and remove the non-fault path from hmm_vma_walk_hole_(). This avoids setting NONE before returning -EBUSY. Also rename the function to hmm_vma_fault() to better describe what it does. Fixes: 2aee09d8c116 ("mm/hmm: change hmm_vma_fault() to allow write fault on page basis") Link: https://lore.kernel.org/r/20200316135310.899364-5-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: simplify hmm_vma_walk_hugetlb_entry()Christoph Hellwig2020-03-261-10/+3
| | | | | | | | | | Remove the rather confusing goto label and just handle the fault case directly in the branch checking for it. Link: https://lore.kernel.org/r/20200316135310.899364-4-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: remove the unused HMM_FAULT_ALLOW_RETRY flagChristoph Hellwig2020-03-261-7/+0
| | | | | | | | | | The HMM_FAULT_ALLOW_RETRY isn't used anywhere in the tree. Remove it and the weird -EAGAIN handling where handle_mm_fault() drops the mmap_sem. Link: https://lore.kernel.org/r/20200316135310.899364-3-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: do not check pmd_protnone twice in hmm_vma_handle_pmd()Jason Gunthorpe2020-03-261-1/+1
| | | | | | | | | | | | | pmd_to_hmm_pfn_flags() already checks it and makes the cpu flags 0. If no fault is requested then the pfns should be returned with the not valid flags. It should not unconditionally fault if faulting is not requested. Fixes: 2aee09d8c116 ("mm/hmm: change hmm_vma_fault() to allow write fault on page basis") Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: add missing call to hmm_pte_need_fault in HMM_PFN_SPECIAL handlingJason Gunthorpe2020-03-261-7/+12
| | | | | | | | | | | | | | | | | Currently if a special PTE is encountered hmm_range_fault() immediately returns EFAULT and sets the HMM_PFN_SPECIAL error output (which nothing uses). EFAULT should only be returned after testing with hmm_pte_need_fault(). Also pte_devmap() and pte_special() are exclusive, and there is no need to check IS_ENABLED, pte_special() is stubbed out to return false on unsupported architectures. Fixes: 992de9a8b751 ("mm/hmm: allow to mirror vma of a file on a DAX backed filesystem") Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: return -EFAULT when setting HMM_PFN_ERROR on requested valid pagesJason Gunthorpe2020-03-261-17/+21
| | | | | | | | | | | | | | | | | hmm_range_fault() should never return 0 if the caller requested a valid page, but the pfns output for that page would be HMM_PFN_ERROR. hmm_pte_need_fault() must always be called before setting HMM_PFN_ERROR to detect if the page is in faulting mode or not. Fix two cases in hmm_vma_walk_pmd() and reorganize some of the duplicated code. Fixes: d08faca018c4 ("mm/hmm: properly handle migration pmd") Fixes: da4c3c735ea4 ("mm/hmm/mirror: helper to snapshot CPU page table") Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: reorganize how !pte_present is handled in hmm_vma_handle_pte()Jason Gunthorpe2020-03-261-20/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The intention with this code is to determine if the caller required the pages to be valid, and if so, then take some action to make them valid. The action varies depending on the page type. In all cases, if the caller doesn't ask for the page, then hmm_range_fault() should not return an error. Revise the implementation to be clearer, and fix some bugs: - hmm_pte_need_fault() must always be called before testing fault or write_fault otherwise the defaults of false apply and the if()'s don't work. This was missed on the is_migration_entry() branch - -EFAULT should not be returned unless hmm_pte_need_fault() indicates fault is required - ie snapshotting should not fail. - For !pte_present() the cpu_flags are always 0, except in the special case of is_device_private_entry(), calling pte_to_hmm_pfn_flags() is confusing. Reorganize the flow so that it always follows the pattern of calling hmm_pte_need_fault() and then checking fault || write_fault. Fixes: 2aee09d8c116 ("mm/hmm: change hmm_vma_fault() to allow write fault on page basis") Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: add missing call to hmm_range_need_fault() before returning EFAULTJason Gunthorpe2020-03-261-11/+8
| | | | | | | | | | | | | All return paths that do EFAULT must call hmm_range_need_fault() to determine if the user requires this page to be valid. If the page cannot be made valid if the user later requires it, due to vma flags in this case, then the return should be HMM_PFN_ERROR. Fixes: a3e0d41c2b1f ("mm/hmm: improve driver API to work and wait over a range") Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: add missing pfns set to hmm_vma_walk_pmd()Jason Gunthorpe2020-03-261-1/+1
| | | | | | | | | | | | All success exit paths from the walker functions must set the pfns array. A migration entry with no required fault is a HMM_PFN_NONE return, just like the pte case. Fixes: d08faca018c4 ("mm/hmm: properly handle migration pmd") Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: do not call hmm_vma_walk_hole() while holding a spinlockJason Gunthorpe2020-03-261-7/+7
| | | | | | | | | | | | | | | This eventually calls into handle_mm_fault() which is a sleeping function. Release the lock first. hmm_vma_walk_hole() does not touch the contents of the PUD, so it does not need the lock. Fixes: 3afc423632a1 ("mm: pagewalk: add p4d_entry() and pgd_entry()") Cc: Steven Price <steven.price@arm.com> Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Steven Price <steven.price@arm.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: add missing unmaps of the ptep during hmm_vma_handle_pte()Jason Gunthorpe2020-03-261-2/+6
| | | | | | | | | | | | | | Many of the direct returns of error skipped doing the pte_unmap(). All non zero exit paths must unmap the pte. The pte_unmap() is split unnaturally like this because some of the error exit paths trigger a sleep and must release the lock before sleeping. Fixes: 992de9a8b751 ("mm/hmm: allow to mirror vma of a file on a DAX backed filesystem") Fixes: 53f5c3f489ec ("mm/hmm: factor out pte and pmd handling to simplify hmm_vma_walk_pmd()") Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm: pagewalk: add 'depth' parameter to pte_holeSteven Price2020-02-041-4/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The pte_hole() callback is called at multiple levels of the page tables. Code dumping the kernel page tables needs to know what at what depth the missing entry is. Add this is an extra parameter to pte_hole(). When the depth isn't know (e.g. processing a vma) then -1 is passed. The depth that is reported is the actual level where the entry is missing (ignoring any folding that is in place), i.e. any levels where PTRS_PER_P?D is set to 1 are ignored. Note that depth starts at 0 for a PGD so that PUD/PMD/PTE retain their natural numbers as levels 2/3/4. Link: http://lkml.kernel.org/r/20191218162402.45610-16-steven.price@arm.com Signed-off-by: Steven Price <steven.price@arm.com> Tested-by: Zong Li <zong.li@sifive.com> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Alexandre Ghiti <alex@ghiti.fr> Cc: Andy Lutomirski <luto@kernel.org> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Hogan <jhogan@kernel.org> Cc: James Morse <james.morse@arm.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: "Liang, Kan" <kan.liang@linux.intel.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Paul Burton <paul.burton@mips.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm: pagewalk: add p4d_entry() and pgd_entry()Steven Price2020-02-041-26/+32
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | pgd_entry() and pud_entry() were removed by commit 0b1fbfe50006c410 ("mm/pagewalk: remove pgd_entry() and pud_entry()") because there were no users. We're about to add users so reintroduce them, along with p4d_entry() as we now have 5 levels of tables. Note that commit a00cc7d9dd93d66a ("mm, x86: add support for PUD-sized transparent hugepages") already re-added pud_entry() but with different semantics to the other callbacks. This commit reverts the semantics back to match the other callbacks. To support hmm.c which now uses the new semantics of pud_entry() a new member ('action') of struct mm_walk is added which allows the callbacks to either descend (ACTION_SUBTREE, the default), skip (ACTION_CONTINUE) or repeat the callback (ACTION_AGAIN). hmm.c is then updated to call pud_trans_huge_lock() itself and make use of the splitting/retry logic of the core code. After this change pud_entry() is called for all entries, not just transparent huge pages. [arnd@arndb.de: fix unused variable warning] Link: http://lkml.kernel.org/r/20200107204607.1533842-1-arnd@arndb.de Link: http://lkml.kernel.org/r/20191218162402.45610-12-steven.price@arm.com Signed-off-by: Steven Price <steven.price@arm.com> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Albert Ou <aou@eecs.berkeley.edu> Cc: Alexandre Ghiti <alex@ghiti.fr> Cc: Andy Lutomirski <luto@kernel.org> Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Borislav Petkov <bp@alien8.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David S. Miller <davem@davemloft.net> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Hogan <jhogan@kernel.org> Cc: James Morse <james.morse@arm.com> Cc: Jerome Glisse <jglisse@redhat.com> Cc: "Liang, Kan" <kan.liang@linux.intel.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Paul Burton <paul.burton@mips.com> Cc: Paul Mackerras <paulus@samba.org> Cc: Paul Walmsley <paul.walmsley@sifive.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Russell King <linux@armlinux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Will Deacon <will@kernel.org> Cc: Zong Li <zong.li@sifive.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* mm/hmm: remove hmm_range_dma_map and hmm_range_dma_unmapChristoph Hellwig2019-11-231-147/+0
| | | | | | | | | | These two functions have never been used since they were added. Link: https://lore.kernel.org/r/20191113134528.21187-1-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: John Hubbard <jhubbard@nvidia.com> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: make full use of walk_page_range()Ralph Campbell2019-11-231-64/+56
| | | | | | | | | | | | | | | | | | | | | | | hmm_range_fault() calls find_vma() and walk_page_range() in a loop. This is unnecessary duplication since walk_page_range() calls find_vma() in a loop already. Simplify hmm_range_fault() by defining a walk_test() callback function to filter unhandled vmas. This also fixes a bug where hmm_range_fault() was not checking start >= vma->vm_start before checking vma->vm_flags so hmm_range_fault() could return an error based on the wrong vma for the requested range. It also fixes a bug when the vma has no read access and the caller did not request a fault, there shouldn't be any error return code. Link: https://lore.kernel.org/r/20191104222141.5173-2-rcampbell@nvidia.com Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: remove hmm_mirror and relatedJason Gunthorpe2019-11-231-277/+8
| | | | | | | | | | | The only two users of this are now converted to use mmu_interval_notifier, delete all the code and update hmm.rst. Link: https://lore.kernel.org/r/20191112202231.3856-14-jgg@ziepe.ca Reviewed-by: Jérôme Glisse <jglisse@redhat.com> Tested-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: allow hmm_range to be used with a mmu_interval_notifier or hmm_mirrorJason Gunthorpe2019-11-231-6/+19
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | hmm_mirror's handling of ranges does not use a sequence count which results in this bug: CPU0 CPU1 hmm_range_wait_until_valid(range) valid == true hmm_range_fault(range) hmm_invalidate_range_start() range->valid = false hmm_invalidate_range_end() range->valid = true hmm_range_valid(range) valid == true Where the hmm_range_valid() should not have succeeded. Adding the required sequence count would make it nearly identical to the new mmu_interval_notifier. Instead replace the hmm_mirror stuff with mmu_interval_notifier. Co-existence of the two APIs is the first step. Link: https://lore.kernel.org/r/20191112202231.3856-4-jgg@ziepe.ca Reviewed-by: Jérôme Glisse <jglisse@redhat.com> Tested-by: Philip Yang <Philip.Yang@amd.com> Tested-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: allow snapshot of the special zero pageRalph Campbell2019-10-291-2/+8
| | | | | | | | | | | | | | | | | | If a device driver like nouveau tries to use hmm_range_fault() to access the special shared zero page in system memory, hmm_range_fault() will return -EFAULT and kill the process. Allow hmm_range_fault() to return success (0) when the CPU pagetable entry points to the special shared zero page. page_to_pfn() and pfn_to_page() are defined on the zero page so just handle it like any other page. Link: https://lore.kernel.org/r/20191023195515.13168-3-rcampbell@nvidia.com Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: "Jérôme Glisse" <jglisse@redhat.com> Acked-by: David Hildenbrand <david@redhat.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* pagewalk: separate function pointers from iterator dataChristoph Hellwig2019-09-071-12/+11
| | | | | | | | | | | | | | | | The mm_walk structure currently mixed data and code. Split out the operations vectors into a new mm_walk_ops structure, and while we are changing the API also declare the mm_walk structure inside the walk_page_range and walk_page_vma functions. Based on patch from Linus Torvalds. Link: https://lore.kernel.org/r/20190828141955.22210-3-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com> Reviewed-by: Steven Price <steven.price@arm.com> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm: split out a new pagewalk.h header from mm.hChristoph Hellwig2019-09-071-1/+1
| | | | | | | | | | | | Add a new header for the two handful of users of the walk_page_range / walk_page_vma interface instead of polluting all users of mm.h with it. Link: https://lore.kernel.org/r/20190828141955.22210-2-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Thomas Hellstrom <thellstrom@vmware.com> Reviewed-by: Steven Price <steven.price@arm.com> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: hmm_range_fault() infinite loopRalph Campbell2019-08-271-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Normally, callers to handle_mm_fault() are supposed to check the vma->vm_flags first. hmm_range_fault() checks for VM_READ but doesn't check for VM_WRITE if the caller requests a page to be faulted in with write permission (via the hmm_range.pfns[] value). If the vma is write protected, this can result in an infinite loop: hmm_range_fault() walk_page_range() ... hmm_vma_walk_hole() hmm_vma_walk_hole_() hmm_vma_do_fault() handle_mm_fault(FAULT_FLAG_WRITE) /* returns VM_FAULT_WRITE */ /* returns -EBUSY */ /* returns -EBUSY */ /* returns -EBUSY */ /* loops on -EBUSY and range->valid */ Prevent this by checking for vma->vm_flags & VM_WRITE before calling handle_mm_fault(). Link: https://lore.kernel.org/r/20190823221753.2514-3-rcampbell@nvidia.com Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: hmm_range_fault() NULL pointer bugRalph Campbell2019-08-271-4/+9
| | | | | | | | | | | | | | | | | | | | | | | Although hmm_range_fault() calls find_vma() to make sure that a vma exists before calling walk_page_range(), hmm_vma_walk_hole() can still be called with walk->vma == NULL if the start and end address are not contained within the vma range. hmm_range_fault() /* calls find_vma() but no range check */ walk_page_range() /* calls find_vma(), sets walk->vma = NULL */ __walk_page_range() walk_pgd_range() walk_p4d_range() walk_pud_range() hmm_vma_walk_hole() hmm_vma_walk_hole_() hmm_vma_do_fault() handle_mm_fault(vma=0) Link: https://lore.kernel.org/r/20190823221753.2514-2-rcampbell@nvidia.com Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: fix hmm_range_fault()'s handling of swapped out pagesYang, Philip2019-08-231-0/+3
| | | | | | | | | | | | | | | | hmm_range_fault() may return NULL pages because some of the pfns are equal to HMM_PFN_NONE. This happens randomly under memory pressure. The reason is during the swapped out page pte path, hmm_vma_handle_pte() doesn't update the fault variable from cpu_flags, so it failed to call hmm_vam_do_fault() to swap the page in. The fix is to call hmm_pte_need_fault() to update fault variable. Fixes: 74eee180b935 ("mm/hmm/mirror: device page fault handler") Link: https://lore.kernel.org/r/20190815205227.7949-1-Philip.Yang@amd.com Signed-off-by: Philip Yang <Philip.Yang@amd.com> Reviewed-by: "Jérôme Glisse" <jglisse@redhat.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* hmm: use mmu_notifier_get/put for 'struct hmm'Jason Gunthorpe2019-08-201-93/+28
| | | | | | | | | | | | | | | | | | | | | | This is a significant simplification, it eliminates all the remaining 'hmm' stuff in mm_struct, eliminates krefing along the critical notifier paths, and takes away all the ugly locking and abuse of page_table_lock. mmu_notifier_get() provides the single struct hmm per struct mm which eliminates mm->hmm. It also directly guarantees that no mmu_notifier op callback is callable while concurrent free is possible, this eliminates all the krefs inside the mmu_notifier callbacks. The remaining krefs in the range code were overly cautious, drivers are already not permitted to free the mirror while a range exists. Link: https://lore.kernel.org/r/20190806231548.25242-6-jgg@ziepe.ca Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Ralph Campbell <rcampbell@nvidia.com> Tested-by: Ralph Campbell <rcampbell@nvidia.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: cleanup the hmm_vma_walk_hugetlb_entry stubChristoph Hellwig2019-08-071-4/+4
| | | | | | | | | | | Stub out the whole function and assign NULL to the .hugetlb_entry method if CONFIG_HUGETLB_PAGE is not set, as the method won't ever be called in that case. Link: https://lore.kernel.org/r/20190806160554.14046-13-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: cleanup the hmm_vma_handle_pmd stubChristoph Hellwig2019-08-071-10/+8
| | | | | | | | | | Stub out the whole function when CONFIG_TRANSPARENT_HUGEPAGE is not set to make the function easier to read. Link: https://lore.kernel.org/r/20190806160554.14046-12-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: only define hmm_vma_walk_pud if neededChristoph Hellwig2019-08-071-13/+16
| | | | | | | | | | | | | We only need the special pud_entry walker if PUD-sized hugepages and pte mappings are supported, else the common pagewalk code will take care of the iteration. Not implementing this callback reduced the amount of code compiled for non-x86 platforms, and also fixes compile failures with other architectures when helpers like pud_pfn are not implemented. Link: https://lore.kernel.org/r/20190806160554.14046-11-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: don't abuse pte_index() in hmm_vma_handle_pmdChristoph Hellwig2019-08-071-1/+1
| | | | | | | | | | | pte_index is an internal arch helper in various architectures, without consistent semantics. Open code that calculation of a PMD index based on the virtual address instead. Link: https://lore.kernel.org/r/20190806160554.14046-10-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: remove the mask variable in hmm_vma_walk_hugetlb_entryChristoph Hellwig2019-08-071-5/+2
| | | | | | | | | The pagewalk code already passes the value as the hmask parameter. Link: https://lore.kernel.org/r/20190806160554.14046-9-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: remove the page_shift member from struct hmm_rangeChristoph Hellwig2019-08-071-33/+9
| | | | | | | | | | | | | All users pass PAGE_SIZE here, and if we wanted to support single entries for huge pages we should really just add a HMM_FAULT_HUGEPAGE flag instead that uses the huge page size instead of having the caller calculate that size once, just for the hmm code to verify it. Link: https://lore.kernel.org/r/20190806160554.14046-8-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Felix Kuehling <Felix.Kuehling@amd.com> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: remove superfluous arguments from hmm_range_registerChristoph Hellwig2019-08-071-15/+5
| | | | | | | | | | | The start, end and page_shift values are all saved in the range structure, so we might as well use that for argument passing. Link: https://lore.kernel.org/r/20190806160554.14046-7-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: remove the unused vma argument to hmm_range_dma_unmapChristoph Hellwig2019-08-071-2/+0
| | | | | | | Link: https://lore.kernel.org/r/20190806160554.14046-6-hch@lst.de Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: remove hmm_range vmaRalph Campbell2019-07-261-1/+0
| | | | | | | | | | | | Since hmm_range_fault() doesn't use the struct hmm_range vma field, remove it. Link: https://lore.kernel.org/r/20190726005650.2566-8-rcampbell@nvidia.com Suggested-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: remove hugetlbfs check in hmm_vma_walk_pmdRalph Campbell2019-07-261-3/+0
| | | | | | | | | | | | | | walk_page_range() will only call hmm_vma_walk_hugetlb_entry() for hugetlbfs pages and doesn't call hmm_vma_walk_pmd() in this case. Therefore, it is safe to remove the check for vma->vm_flags & VM_HUGETLB in hmm_vma_walk_pmd(). Link: https://lore.kernel.org/r/20190726005650.2566-7-rcampbell@nvidia.com Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: merge hmm_range_snapshot into hmm_range_faultChristoph Hellwig2019-07-261-83/+2
| | | | | | | | | | | Add a HMM_FAULT_SNAPSHOT flag so that hmm_range_snapshot can be merged into the almost identical hmm_range_fault function. Link: https://lore.kernel.org/r/20190726005650.2566-5-rcampbell@nvidia.com Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: replace the block argument to hmm_range_fault with a flags valueChristoph Hellwig2019-07-261-37/+37
| | | | | | | | | | | This allows easier expansion to other flags, and also makes the callers a little easier to read. Link: https://lore.kernel.org/r/20190726005650.2566-4-rcampbell@nvidia.com Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: a few more C style and comment clean upsRalph Campbell2019-07-261-22/+17
| | | | | | | | | | | A few more comments and minor programming style clean ups. There should be no functional changes. Link: https://lore.kernel.org/r/20190726005650.2566-3-rcampbell@nvidia.com Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: replace hmm_update with mmu_notifier_rangeRalph Campbell2019-07-261-9/+4
| | | | | | | | | | | | | | The hmm_mirror_ops callback function sync_cpu_device_pagetables() passes a struct hmm_update which is a simplified version of struct mmu_notifier_range. This is unnecessary so replace hmm_update with mmu_notifier_range directly. Link: https://lore.kernel.org/r/20190726005650.2566-2-rcampbell@nvidia.com Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> Reviewed: Christoph Hellwig <hch@lst.de> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com> [jgg: white space tuning] Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
* mm/hmm: comment on VM_FAULT_RETRY semantics in handle_mm_faultJason Gunthorpe2019-07-251-1/+3
| | | | | | | | | | | The magic dropping of mmap_sem when handle_mm_fault returns VM_FAULT_RETRY is rather subtile. Add a comment explaining it. Link: https://lore.kernel.org/r/20190724065258.16603-8-hch@lst.de Tested-by: Ralph Campbell <rcampbell@nvidia.com> Signed-off-by: Jason Gunthorpe <jgg@mellanox.com> [hch: wrote a changelog] Signed-off-by: Christoph Hellwig <hch@lst.de>
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-25 11:04:30 +0000