lkml.org 
[lkml]   [2003]   [Sep]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patches in this message
/
Date
From
SubjectRe: [PATCH] Alternate futex non-page-pinning and COW fix
Jamie Lokier <jamie@shareable.org> wrote:
>
> You will be please to know I have written a complete patch :)

Looks pretty sane to me. A couple of (untested) fixups:



Take mmap_sem for writing around the modification of vma->vm_flags.

But hold it for reading across the populate function: it does I/O and is
slow.



25-akpm/mm/fremap.c | 14 ++++++++------
1 files changed, 8 insertions(+), 6 deletions(-)
diff -puN mm/fremap.c~futex-non-page-pinning-akpm-1 mm/fremap.c
--- 25/mm/fremap.c~futex-non-page-pinning-akpm-1 Wed Sep 3 08:16:30 2003
+++ 25-akpm/mm/fremap.c Wed Sep 3 08:19:21 2003
@@ -144,7 +144,10 @@ long sys_remap_file_pages(unsigned long
return err;
#endif

- down_read(&mm->mmap_sem);
+ /*
+ * vm_flags is protected by down_write(mmap_sem)
+ */
+ down_write(&mm->mmap_sem);

vma = find_vma(mm, start);
/*
@@ -161,13 +164,12 @@ long sys_remap_file_pages(unsigned long
if (start == vma->vm_start && end == vma->vm_end &&
pgoff == vma->vm_pgoff)
vma->vm_flags &= ~VM_NONLINEAR;
-
+ downgrade_write(&mm->mmap_sem);
err = vma->vm_ops->populate(vma, start, size, vma->vm_page_prot,
pgoff, flags & MAP_NONBLOCK);
+ up_read(&mm->mmap_sem);
+ } else {
+ up_write(&mm->mmap_sem);
}
-
- up_read(&mm->mmap_sem);
-
return err;
}
-
_


schedule_timeout() returns in state TASK_RUNNING.


25-akpm/kernel/futex.c | 1 -
1 files changed, 1 deletion(-)
diff -puN kernel/futex.c~futex-non-page-pinning-akpm-2 kernel/futex.c
--- 25/kernel/futex.c~futex-non-page-pinning-akpm-2 Wed Sep 3 08:31:34 2003
+++ 25-akpm/kernel/futex.c Wed Sep 3 08:31:47 2003
@@ -358,7 +358,6 @@ static inline int futex_wait(unsigned lo

spin_unlock(&futex_lock);
time = schedule_timeout(time);
- set_current_state(TASK_RUNNING);

/*
* NOTE: we don't remove ourselves from the waitqueue because
_

-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2005-03-22 13:48    [from the cache]
©2003-2011 Jasper Spaans