linux-kernel - [PATCH 48/64] arch/tile: use mm locking wrappers

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Date:   Mon,  5 Feb 2018 02:27:38 +0100
From:   Davidlohr Bueso <dbueso@...e.de>
To:     akpm@...ux-foundation.org, mingo@...nel.org
Cc:     peterz@...radead.org, ldufour@...ux.vnet.ibm.com, jack@...e.cz,
        mhocko@...nel.org, kirill.shutemov@...ux.intel.com,
        mawilcox@...rosoft.com, mgorman@...hsingularity.net,
        dave@...olabs.net, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, Davidlohr Bueso <dbueso@...e.de>
Subject: [PATCH 48/64] arch/tile: use mm locking wrappers

From: Davidlohr Bueso <dave@...olabs.net>

* THIS IS A HACK *

Breaks arch/um/. See comment in fix_range_common().

Signed-off-by: Davidlohr Bueso <dbueso@...e.de>
---
 arch/um/include/asm/mmu_context.h |  5 +++--
 arch/um/kernel/tlb.c              | 12 +++++++++++-
 arch/um/kernel/trap.c             |  6 +++---
 3 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/arch/um/include/asm/mmu_context.h b/arch/um/include/asm/mmu_context.h
index 98cc3e36385a..7dc202c611db 100644
--- a/arch/um/include/asm/mmu_context.h
+++ b/arch/um/include/asm/mmu_context.h
@@ -49,14 +49,15 @@ extern void force_flush_all(void);
 
 static inline void activate_mm(struct mm_struct *old, struct mm_struct *new)
 {
+	DEFINE_RANGE_LOCK_FULL(mmrange);
 	/*
 	 * This is called by fs/exec.c and sys_unshare()
 	 * when the new ->mm is used for the first time.
 	 */
 	__switch_mm(&new->context.id);
-	down_write(&new->mmap_sem);
+        mm_write_lock(new, &mmrange);
 	uml_setup_stubs(new);
-	up_write(&new->mmap_sem);
+	mm_write_unlock(new, &mmrange);
 }
 
 static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, 
diff --git a/arch/um/kernel/tlb.c b/arch/um/kernel/tlb.c
index 37508b190106..eeeeb048b6f4 100644
--- a/arch/um/kernel/tlb.c
+++ b/arch/um/kernel/tlb.c
@@ -297,10 +297,20 @@ void fix_range_common(struct mm_struct *mm, unsigned long start_addr,
 
 	/* This is not an else because ret is modified above */
 	if (ret) {
+		/*
+		 * FIXME: this is _wrong_ and will break arch/um.
+		 *
+		 *  The right thing to do is modify the flush_tlb_range()
+		 *  api, but that in turn would require file_operations
+		 *  knowing about mmrange... Compiles cleanly, but sucks
+		 *  otherwise.
+		 */
+		DEFINE_RANGE_LOCK_FULL(mmrange);
+
 		printk(KERN_ERR "fix_range_common: failed, killing current "
 		       "process: %d\n", task_tgid_vnr(current));
 		/* We are under mmap_sem, release it such that current can terminate */
-		up_write(&current->mm->mmap_sem);
+		mm_write_unlock(current->mm, &mmrange);
 		force_sig(SIGKILL, current);
 		do_signal(&current->thread.regs);
 	}
diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index e632a14e896e..14dcb83d00a9 100644
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c
@@ -47,7 +47,7 @@ int handle_page_fault(unsigned long address, unsigned long ip,
 	if (is_user)
 		flags |= FAULT_FLAG_USER;
 retry:
-	down_read(&mm->mmap_sem);
+	mm_read_lock(mm, &mmrange);
 	vma = find_vma(mm, address);
 	if (!vma)
 		goto out;
@@ -123,7 +123,7 @@ int handle_page_fault(unsigned long address, unsigned long ip,
 #endif
 	flush_tlb_page(vma, address);
 out:
-	up_read(&mm->mmap_sem);
+	mm_read_unlock(mm, &mmrange);
 out_nosemaphore:
 	return err;
 
@@ -132,7 +132,7 @@ int handle_page_fault(unsigned long address, unsigned long ip,
 	 * We ran out of memory, call the OOM killer, and return the userspace
 	 * (which will retry the fault, or kill us if we got oom-killed).
 	 */
-	up_read(&mm->mmap_sem);
+	mm_read_unlock(mm, &mmrange);
 	if (!is_user)
 		goto out_nosemaphore;
 	pagefault_out_of_memory();
-- 
2.13.6