diff options
| author | Hugh Dickins <hugh@veritas.com> | 2004-11-18 22:54:47 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2004-11-18 22:54:47 -0800 |
| commit | b6de40561faafcc3f44e1acfa942c46ac8d5ad6e (patch) | |
| tree | bbf68b8a377c7cc4c604e3df37756ac69a4ac8e3 /mm | |
| parent | 2f8b7fcfca8b477d91d216f79625cdb3aa92ec5c (diff) | |
| download | history-b6de40561faafcc3f44e1acfa942c46ac8d5ad6e.tar.gz | |
[PATCH] mlock-vs-VM_IO hang fix
With Andrea Arcangeli <andrea@novell.com>
Fix a hang which occurs when mlock() encounters a mapping of /dev/mem.
These have VM_IO set. follow_page() keeps returning zero (not a valid pfn)
and handle_mm_fault() keeps on returning VM_FAULT_MINOR (there's a pte
there), so get_user_pages() locks up.
The patch changes get_user_pages() to just bale out when it hits a VM_IO
region. make_pages_present() is taught to ignore the resulting -EFAULT.
We still have two bugs:
a) If a process has a VM_IO vma, get_user_pages() will bale early,
without having considered the vmas at higher virtual addresses.
As do_mlock() also walks the vma list this bug is fairly benign, but
get_user_pages() is doing the wrong thing there.
b) The `len' argument to get_user_pages should be long, not int. We
presently have a 16TB limit on 64-bit.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/memory.c | 2 | ||||
| -rw-r--r-- | mm/mlock.c | 3 |
2 files changed, 3 insertions, 2 deletions
diff --git a/mm/memory.c b/mm/memory.c index 2c2ff72c118ef5..0a80f55f9f2ad7 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -761,7 +761,7 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, continue; } - if (!vma || (pages && (vma->vm_flags & VM_IO)) + if (!vma || (vma->vm_flags & VM_IO) || !(flags & vma->vm_flags)) return i ? : -EFAULT; diff --git a/mm/mlock.c b/mm/mlock.c index 9cdfcf0036fede..4a00277487bad9 100644 --- a/mm/mlock.c +++ b/mm/mlock.c @@ -47,7 +47,8 @@ static int mlock_fixup(struct vm_area_struct * vma, pages = (end - start) >> PAGE_SHIFT; if (newflags & VM_LOCKED) { pages = -pages; - ret = make_pages_present(start, end); + if (!(newflags & VM_IO)) + ret = make_pages_present(start, end); } vma->vm_mm->locked_vm -= pages; |