[RFC PATCH 1/2] mm/filemap: Retry fault by VMA lock if the lock was released for I/O

[Barry Song <21cnbao@gmail.com>]

From: Oven Liyang <liyangouwen1@oppo.com>

If the current page fault is using the per-VMA lock, and we only released
the lock to wait for I/O completion (e.g., using folio_lock()), then when
the fault is retried after the I/O completes, it should still qualify for
the per-VMA-lock path.

Cc: Russell King <linux@armlinux.org.uk>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Paul Walmsley <pjw@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: x86@kernel.org
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Jarkko Sakkinen <jarkko@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ada Couprie Diaz <ada.coupriediaz@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Kristina Martšenko <kristina.martsenko@arm.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Yeoreum Yun <yeoreum.yun@arm.com>
Cc: Wentao Guan <guanwentao@uniontech.com>
Cc: Thorsten Blum <thorsten.blum@linux.dev>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Yunhui Cui <cuiyunhui@bytedance.com>
Cc: Nam Cao <namcao@linutronix.de>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: loongarch@lists.linux.dev
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-riscv@lists.infradead.org
Cc: linux-s390@vger.kernel.org
Cc: linux-mm@kvack.org
Cc: linux-fsdevel@vger.kernel.org
Cc: Chris Li <chrisl@kernel.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Baoquan He <bhe@redhat.com>
Signed-off-by: Oven Liyang <liyangouwen1@oppo.com>
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
---
 arch/arm/mm/fault.c       | 5 +++++
 arch/arm64/mm/fault.c     | 5 +++++
 arch/loongarch/mm/fault.c | 4 ++++
 arch/powerpc/mm/fault.c   | 5 ++++-
 arch/riscv/mm/fault.c     | 4 ++++
 arch/s390/mm/fault.c      | 4 ++++
 arch/x86/mm/fault.c       | 4 ++++
 include/linux/mm_types.h  | 9 +++++----
 mm/filemap.c              | 5 ++++-
 9 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index 2bc828a1940c..49fc0340821c 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c
@@ -313,6 +313,7 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 	if (!(flags & FAULT_FLAG_USER))
 		goto lock_mmap;
 
+retry_vma:
 	vma = lock_vma_under_rcu(mm, addr);
 	if (!vma)
 		goto lock_mmap;
@@ -342,6 +343,10 @@ do_page_fault(unsigned long addr, unsigned int fsr, struct pt_regs *regs)
 			goto no_context;
 		return 0;
 	}
+
+	/* If the first try is only about waiting for the I/O to complete */
+	if (fault & VM_FAULT_RETRY_VMA)
+		goto retry_vma;
 lock_mmap:
 
 retry:
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 125dfa6c613b..842f50b99d3e 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -622,6 +622,7 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
 	if (!(mm_flags & FAULT_FLAG_USER))
 		goto lock_mmap;
 
+retry_vma:
 	vma = lock_vma_under_rcu(mm, addr);
 	if (!vma)
 		goto lock_mmap;
@@ -668,6 +669,10 @@ static int __kprobes do_page_fault(unsigned long far, unsigned long esr,
 			goto no_context;
 		return 0;
 	}
+
+	/* If the first try is only about waiting for the I/O to complete */
+	if (fault & VM_FAULT_RETRY_VMA)
+		goto retry_vma;
 lock_mmap:
 
 retry:
diff --git a/arch/loongarch/mm/fault.c b/arch/loongarch/mm/fault.c
index 2c93d33356e5..738f495560c0 100644
--- a/arch/loongarch/mm/fault.c
+++ b/arch/loongarch/mm/fault.c
@@ -219,6 +219,7 @@ static void __kprobes __do_page_fault(struct pt_regs *regs,
 	if (!(flags & FAULT_FLAG_USER))
 		goto lock_mmap;
 
+retry_vma:
 	vma = lock_vma_under_rcu(mm, address);
 	if (!vma)
 		goto lock_mmap;
@@ -265,6 +266,9 @@ static void __kprobes __do_page_fault(struct pt_regs *regs,
 			no_context(regs, write, address);
 		return;
 	}
+	/* If the first try is only about waiting for the I/O to complete */
+	if (fault & VM_FAULT_RETRY_VMA)
+		goto retry_vma;
 lock_mmap:
 
 retry:
diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 806c74e0d5ab..cb7ffc20c760 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c
@@ -487,6 +487,7 @@ static int ___do_page_fault(struct pt_regs *regs, unsigned long address,
 	if (!(flags & FAULT_FLAG_USER))
 		goto lock_mmap;
 
+retry_vma:
 	vma = lock_vma_under_rcu(mm, address);
 	if (!vma)
 		goto lock_mmap;
@@ -516,7 +517,9 @@ static int ___do_page_fault(struct pt_regs *regs, unsigned long address,
 
 	if (fault_signal_pending(fault, regs))
 		return user_mode(regs) ? 0 : SIGBUS;
-
+	/* If the first try is only about waiting for the I/O to complete */
+	if (fault & VM_FAULT_RETRY_VMA)
+		goto retry_vma;
 lock_mmap:
 
 	/* When running in the kernel we expect faults to occur only to
diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
index 04ed6f8acae4..b94cf57c2b9a 100644
--- a/arch/riscv/mm/fault.c
+++ b/arch/riscv/mm/fault.c
@@ -347,6 +347,7 @@ void handle_page_fault(struct pt_regs *regs)
 	if (!(flags & FAULT_FLAG_USER))
 		goto lock_mmap;
 
+retry_vma:
 	vma = lock_vma_under_rcu(mm, addr);
 	if (!vma)
 		goto lock_mmap;
@@ -376,6 +377,9 @@ void handle_page_fault(struct pt_regs *regs)
 			no_context(regs, addr);
 		return;
 	}
+	/* If the first try is only about waiting for the I/O to complete */
+	if (fault & VM_FAULT_RETRY_VMA)
+		goto retry_vma;
 lock_mmap:
 
 retry:
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index e1ad05bfd28a..8d91c6495e13 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c
@@ -286,6 +286,7 @@ static void do_exception(struct pt_regs *regs, int access)
 		flags |= FAULT_FLAG_WRITE;
 	if (!(flags & FAULT_FLAG_USER))
 		goto lock_mmap;
+retry_vma:
 	vma = lock_vma_under_rcu(mm, address);
 	if (!vma)
 		goto lock_mmap;
@@ -310,6 +311,9 @@ static void do_exception(struct pt_regs *regs, int access)
 			handle_fault_error_nolock(regs, 0);
 		return;
 	}
+	/* If the first try is only about waiting for the I/O to complete */
+	if (fault & VM_FAULT_RETRY_VMA)
+		goto retry_vma;
 lock_mmap:
 retry:
 	vma = lock_mm_and_find_vma(mm, address, regs);
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 998bd807fc7b..6023d0083903 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -1324,6 +1324,7 @@ void do_user_addr_fault(struct pt_regs *regs,
 	if (!(flags & FAULT_FLAG_USER))
 		goto lock_mmap;
 
+retry_vma:
 	vma = lock_vma_under_rcu(mm, address);
 	if (!vma)
 		goto lock_mmap;
@@ -1353,6 +1354,9 @@ void do_user_addr_fault(struct pt_regs *regs,
 						 ARCH_DEFAULT_PKEY);
 		return;
 	}
+	/* If the first try is only about waiting for the I/O to complete */
+	if (fault & VM_FAULT_RETRY_VMA)
+		goto retry_vma;
 lock_mmap:
 
 retry:
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index b71625378ce3..12b2d65ef1b9 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -1670,10 +1670,11 @@ enum vm_fault_reason {
 	VM_FAULT_NOPAGE         = (__force vm_fault_t)0x000100,
 	VM_FAULT_LOCKED         = (__force vm_fault_t)0x000200,
 	VM_FAULT_RETRY          = (__force vm_fault_t)0x000400,
-	VM_FAULT_FALLBACK       = (__force vm_fault_t)0x000800,
-	VM_FAULT_DONE_COW       = (__force vm_fault_t)0x001000,
-	VM_FAULT_NEEDDSYNC      = (__force vm_fault_t)0x002000,
-	VM_FAULT_COMPLETED      = (__force vm_fault_t)0x004000,
+	VM_FAULT_RETRY_VMA      = (__force vm_fault_t)0x000800,
+	VM_FAULT_FALLBACK       = (__force vm_fault_t)0x001000,
+	VM_FAULT_DONE_COW       = (__force vm_fault_t)0x002000,
+	VM_FAULT_NEEDDSYNC      = (__force vm_fault_t)0x004000,
+	VM_FAULT_COMPLETED      = (__force vm_fault_t)0x008000,
 	VM_FAULT_HINDEX_MASK    = (__force vm_fault_t)0x0f0000,
 };
 
diff --git a/mm/filemap.c b/mm/filemap.c
index 7d15a9c216ef..57dfd2211109 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3464,6 +3464,7 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
 	struct folio *folio;
 	vm_fault_t ret = 0;
 	bool mapping_locked = false;
+	bool retry_by_vma_lock = false;
 
 	max_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
 	if (unlikely(index >= max_idx))
@@ -3560,6 +3561,8 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
 	 */
 	if (fpin) {
 		folio_unlock(folio);
+		if (vmf->flags & FAULT_FLAG_VMA_LOCK)
+			retry_by_vma_lock = true;
 		goto out_retry;
 	}
 	if (mapping_locked)
@@ -3610,7 +3613,7 @@ vm_fault_t filemap_fault(struct vm_fault *vmf)
 		filemap_invalidate_unlock_shared(mapping);
 	if (fpin)
 		fput(fpin);
-	return ret | VM_FAULT_RETRY;
+	return ret | VM_FAULT_RETRY | (retry_by_vma_lock ? VM_FAULT_RETRY_VMA : 0);
 }
 EXPORT_SYMBOL(filemap_fault);
 
-- 
2.39.3 (Apple Git-146)