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Message-ID: <20080923224751.GA2790@google.com>
Date: Tue, 23 Sep 2008 15:47:52 -0700
From: sqazi@...gle.com (Salman Qazi)
To: akpm@...ux-foundation.org
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: mlock: Make the mlock system call interruptible by fatal
> Andrew Morton wrote:
>
>This isn't a terribly good interface. Someone could now call
> __get_user_pages() with pages!=NULL and interruptible=1 and they would
> get a return value of -EINTR, even though some page*'s were placed in
> their pages array.
>
> That caller now has no way of knowing how many pages need to be
> released to clean up.
>
> Can we do
>
> return i ? i : -EINTR;
>
> in the usual fashion?
Fixed.
Make the mlock system call interruptible by fatal signals, so that programs
that are mlocking a large number of pages terminate quickly when killed.
Signed-off-by: Salman Qazi <sqazi@...gle.com>
---
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 72a15dc..a2531e6 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -807,7 +807,8 @@ static inline int handle_mm_fault(struct mm_struct *mm,
}
#endif
-extern int make_pages_present(unsigned long addr, unsigned long end);
+extern int make_pages_present(unsigned long addr, unsigned long end,
+ int interruptible);
extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write);
int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, unsigned long start,
diff --git a/mm/fremap.c b/mm/fremap.c
index 7881638..f5eff74 100644
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -223,7 +223,7 @@ asmlinkage long sys_remap_file_pages(unsigned long start, unsigned long size,
downgrade_write(&mm->mmap_sem);
has_write_lock = 0;
}
- make_pages_present(start, start+size);
+ make_pages_present(start, start+size, 0);
}
/*
diff --git a/mm/memory.c b/mm/memory.c
index 1002f47..f6f8742 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1129,9 +1129,10 @@ static inline int use_zero_page(struct vm_area_struct *vma)
return !vma->vm_ops || !vma->vm_ops->fault;
}
-int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
- unsigned long start, int len, int write, int force,
- struct page **pages, struct vm_area_struct **vmas)
+static int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
+ unsigned long start, int len, int write, int force,
+ struct page **pages, struct vm_area_struct **vmas,
+ int interruptible)
{
int i;
unsigned int vm_flags;
@@ -1223,6 +1224,8 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
cond_resched();
while (!(page = follow_page(vma, start, foll_flags))) {
int ret;
+ if (interruptible && fatal_signal_pending(tsk))
+ return i ? i : -EINTR;
ret = handle_mm_fault(mm, vma, start,
foll_flags & FOLL_WRITE);
if (ret & VM_FAULT_ERROR) {
@@ -1266,6 +1269,14 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
} while (len);
return i;
}
+
+int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
+ unsigned long start, int len, int write, int force,
+ struct page **pages, struct vm_area_struct **vmas)
+{
+ return __get_user_pages(tsk, mm, start, len, write, force,
+ pages, vmas, 0);
+}
EXPORT_SYMBOL(get_user_pages);
pte_t *get_locked_pte(struct mm_struct *mm, unsigned long addr,
@@ -2758,7 +2769,7 @@ int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
}
#endif /* __PAGETABLE_PMD_FOLDED */
-int make_pages_present(unsigned long addr, unsigned long end)
+int make_pages_present(unsigned long addr, unsigned long end, int interruptible)
{
int ret, len, write;
struct vm_area_struct * vma;
@@ -2770,8 +2781,8 @@ int make_pages_present(unsigned long addr, unsigned long end)
BUG_ON(addr >= end);
BUG_ON(end > vma->vm_end);
len = DIV_ROUND_UP(end, PAGE_SIZE) - addr/PAGE_SIZE;
- ret = get_user_pages(current, current->mm, addr,
- len, write, 0, NULL, NULL);
+ ret = __get_user_pages(current, current->mm, addr,
+ len, write, 0, NULL, NULL, interruptible);
if (ret < 0) {
/*
SUS require strange return value to mlock
diff --git a/mm/mlock.c b/mm/mlock.c
index 01fbe93..5586ee4 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -73,7 +73,7 @@ success:
if (newflags & VM_LOCKED) {
pages = -pages;
if (!(newflags & VM_IO))
- ret = make_pages_present(start, end);
+ ret = make_pages_present(start, end, 1);
}
mm->locked_vm -= pages;
diff --git a/mm/mmap.c b/mm/mmap.c
index e7a5a68..afb8e39 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1225,10 +1225,10 @@ out:
vm_stat_account(mm, vm_flags, file, len >> PAGE_SHIFT);
if (vm_flags & VM_LOCKED) {
mm->locked_vm += len >> PAGE_SHIFT;
- make_pages_present(addr, addr + len);
+ make_pages_present(addr, addr + len, 0);
}
if ((flags & MAP_POPULATE) && !(flags & MAP_NONBLOCK))
- make_pages_present(addr, addr + len);
+ make_pages_present(addr, addr + len, 0);
return addr;
unmap_and_free_vma:
@@ -1701,7 +1701,7 @@ find_extend_vma(struct mm_struct *mm, unsigned long addr)
if (!prev || expand_stack(prev, addr))
return NULL;
if (prev->vm_flags & VM_LOCKED)
- make_pages_present(addr, prev->vm_end);
+ make_pages_present(addr, prev->vm_end, 0);
return prev;
}
#else
@@ -1728,7 +1728,7 @@ find_extend_vma(struct mm_struct * mm, unsigned long addr)
if (expand_stack(vma, addr))
return NULL;
if (vma->vm_flags & VM_LOCKED)
- make_pages_present(addr, start);
+ make_pages_present(addr, start, 0);
return vma;
}
#endif
@@ -2049,7 +2049,7 @@ out:
mm->total_vm += len >> PAGE_SHIFT;
if (flags & VM_LOCKED) {
mm->locked_vm += len >> PAGE_SHIFT;
- make_pages_present(addr, addr + len);
+ make_pages_present(addr, addr + len, 0);
}
return addr;
}
diff --git a/mm/mremap.c b/mm/mremap.c
index 1a77439..c83ffcc 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -239,7 +239,7 @@ static unsigned long move_vma(struct vm_area_struct *vma,
mm->locked_vm += new_len >> PAGE_SHIFT;
if (new_len > old_len)
make_pages_present(new_addr + old_len,
- new_addr + new_len);
+ new_addr + new_len, 0);
}
return new_addr;
@@ -380,7 +380,7 @@ unsigned long do_mremap(unsigned long addr,
if (vma->vm_flags & VM_LOCKED) {
mm->locked_vm += pages;
make_pages_present(addr + old_len,
- addr + new_len);
+ addr + new_len, 0);
}
ret = addr;
goto out;
---
--
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