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bp@alien8.de, brauner@kernel.org, bsegall@google.com, corbet@lwn.net, dave.hansen@linux.intel.com, david@redhat.com, dietmar.eggemann@arm.com, ebiederm@xmission.com, hpa@zytor.com, jakub.wartak@mailbox.org, jannh@google.com, juri.lelli@redhat.com, khalid@kernel.org, liam.howlett@oracle.com, linyongting@bytedance.com, lorenzo.stoakes@oracle.com, luto@kernel.org, markhemm@googlemail.com, maz@kernel.org, mhiramat@kernel.org, mgorman@suse.de, mhocko@suse.com, mingo@redhat.com, muchun.song@linux.dev, neilb@suse.de, osalvador@suse.de, pcc@google.com, peterz@infradead.org, pfalcato@suse.de, rostedt@goodmis.org, rppt@kernel.org, shakeel.butt@linux.dev, surenb@google.com, tglx@linutronix.de, vasily.averin@linux.dev, vbabka@suse.cz, vincent.guittot@linaro.org, viro@zeniv.linux.org.uk, vschneid@redhat.com, willy@infradead.org, x86@kernel.org, xhao@linux.alibaba.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Subject: [PATCH v3 14/22] x86/mm: enable page 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/kkDSoTtufo/KHISsiVO496RtwDYt3u+ADlHUI/PYBhH7CK8g/RgQHlRURrpFOWmxY1Owiy0ICmipvDCPwBEBeIyMIay31b/wlcA58gzA0h+GwdX4bAucP7eib+CRagTb7ocqG3WwJ4mnk1ndafZYYGcQJoUFqDMup3D6ttrmwHwCcY7a6pG8uOgsfh7my5U7BYsVJeaS0m8+OGmrAKBUW640NA2JXqFhAAbfli5JOKBR+EE= 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: Enable x86 support for handling page faults in an mshare region by redirecting page faults to operate on the mshare mm_struct and vmas contained in it. Some permissions checks are done using vma flags in architecture-specfic fault handling code so the actual vma needed to complete the handling is acquired before calling handle_mm_fault(). Because of this an ARCH_SUPPORTS_MSHARE config option is added. Signed-off-by: Anthony Yznaga --- arch/Kconfig | 3 +++ arch/x86/Kconfig | 1 + arch/x86/mm/fault.c | 40 +++++++++++++++++++++++++++++++++++++++- mm/Kconfig | 2 +- 4 files changed, 44 insertions(+), 2 deletions(-) diff --git a/arch/Kconfig b/arch/Kconfig index d1b4ffd6e085..2e10a11fc442 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -1676,6 +1676,9 @@ config HAVE_ARCH_PFN_VALID config ARCH_SUPPORTS_DEBUG_PAGEALLOC bool +config ARCH_SUPPORTS_MSHARE + bool + config ARCH_SUPPORTS_PAGE_TABLE_CHECK bool diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 58d890fe2100..1ad252eec417 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -124,6 +124,7 @@ config X86 select ARCH_SUPPORTS_ATOMIC_RMW select ARCH_SUPPORTS_DEBUG_PAGEALLOC select ARCH_SUPPORTS_HUGETLBFS + select ARCH_SUPPORTS_MSHARE if X86_64 select ARCH_SUPPORTS_PAGE_TABLE_CHECK if X86_64 select ARCH_SUPPORTS_NUMA_BALANCING if X86_64 select ARCH_SUPPORTS_KMAP_LOCAL_FORCE_MAP if NR_CPUS <= 4096 diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 998bd807fc7b..2a7df3aa13b4 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1215,6 +1215,8 @@ void do_user_addr_fault(struct pt_regs *regs, struct mm_struct *mm; vm_fault_t fault; unsigned int flags = FAULT_FLAG_DEFAULT; + bool is_shared_vma; + unsigned long addr; tsk = current; mm = tsk->mm; @@ -1328,6 +1330,12 @@ void do_user_addr_fault(struct pt_regs *regs, if (!vma) goto lock_mmap; + /* mshare does not support per-VMA locks yet */ + if (vma_is_mshare(vma)) { + vma_end_read(vma); + goto lock_mmap; + } + if (unlikely(access_error(error_code, vma))) { bad_area_access_error(regs, error_code, address, NULL, vma); count_vm_vma_lock_event(VMA_LOCK_SUCCESS); @@ -1356,17 +1364,38 @@ void do_user_addr_fault(struct pt_regs *regs, lock_mmap: retry: + addr = address; + is_shared_vma = false; vma = lock_mm_and_find_vma(mm, address, regs); if (unlikely(!vma)) { bad_area_nosemaphore(regs, error_code, address); return; } + if (unlikely(vma_is_mshare(vma))) { + fault = find_shared_vma(&vma, &addr); + + if (fault) { + mmap_read_unlock(mm); + goto done; + } + + if (!vma) { + mmap_read_unlock(mm); + bad_area_nosemaphore(regs, error_code, address); + return; + } + + is_shared_vma = true; + } + /* * Ok, we have a good vm_area for this memory access, so * we can handle it.. */ if (unlikely(access_error(error_code, vma))) { + if (unlikely(is_shared_vma)) + mmap_read_unlock(vma->vm_mm); bad_area_access_error(regs, error_code, address, mm, vma); return; } @@ -1384,7 +1413,14 @@ void do_user_addr_fault(struct pt_regs *regs, * userland). The return to userland is identified whenever * FAULT_FLAG_USER|FAULT_FLAG_KILLABLE are both set in flags. */ - fault = handle_mm_fault(vma, address, flags, regs); + fault = handle_mm_fault(vma, addr, flags, regs); + + /* + * If the lock on the shared mm has been released, release the lock + * on the task's mm now. + */ + if (unlikely(is_shared_vma) && (fault & (VM_FAULT_COMPLETED | VM_FAULT_RETRY))) + mmap_read_unlock(mm); if (fault_signal_pending(fault, regs)) { /* @@ -1412,6 +1448,8 @@ void do_user_addr_fault(struct pt_regs *regs, goto retry; } + if (unlikely(is_shared_vma)) + mmap_read_unlock(vma->vm_mm); mmap_read_unlock(mm); done: if (likely(!(fault & VM_FAULT_ERROR))) diff --git a/mm/Kconfig b/mm/Kconfig index 8b50e9785729..824da2a481f9 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -1402,7 +1402,7 @@ config FIND_NORMAL_PAGE config MSHARE bool "Mshare" - depends on MMU + depends on MMU && ARCH_SUPPORTS_MSHARE help Enable msharefs: A pseudo filesystem that allows multiple processes to share kernel resources for mapping shared pages. A file created on -- 2.47.1