lkml.org 
[lkml]   [2009]   [Jun]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH 2/5] HWPOISON: fix tasklist_lock/anon_vma locking order
On Fri, Jun 12, 2009 at 06:03:08PM +0800, Andi Kleen wrote:
> On Thu, Jun 11, 2009 at 10:22:41PM +0800, Wu Fengguang wrote:
> > To avoid possible deadlock. Proposed by Nick Piggin:
>
> I disagree with the description. There's no possible deadlock right now.
> It would be purely out of paranoia.
>
> >
> > You have tasklist_lock(R) nesting outside i_mmap_lock, and inside anon_vma
> > lock. And anon_vma lock nests inside i_mmap_lock.
> >
> > This seems fragile. If rwlocks ever become FIFO or tasklist_lock changes
>
> I was a bit dubious on this reasoning. If rwlocks become FIFO a lot of
> stuff will likely break.
>
> > type (maybe -rt kernels do it), then you could have a task holding
>
> I think they tried but backed off quickly again
>
> It's ok with a less scare-mongering description.

Why not merge it into the original patch and add a simple changelog
line there? I tried the last 6.5 patchset and it didn't apply cleanly
to the latest -mm tree. And this patch was updated:

---
HWPOISON: Refactor truncate to allow direct truncating of page v3
From: Nick Piggin <npiggin@suse.de>

Extract out truncate_inode_page() out of the truncate path so that
it can be used by memory-failure.c

[AK: description, headers, fix typos]
v2: Some white space changes from Fengguang Wu
v3: add comments

Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
include/linux/mm.h | 2 ++
mm/truncate.c | 34 ++++++++++++++++++++++------------
2 files changed, 24 insertions(+), 12 deletions(-)

--- linux.orig/mm/truncate.c
+++ linux/mm/truncate.c
@@ -135,6 +135,26 @@ invalidate_complete_page(struct address_
return ret;
}

+/*
+ * Remove one page from its pagecache mapping. The page must be locked.
+ * This does not truncate the file on disk, it performs the pagecache
+ * side of the truncate operation. Dirty data will be discarded, and
+ * concurrent page references are ignored.
+ *
+ * Generic mm/fs code cannot call this on filesystem metadata mappings
+ * because those can assume that a page reference is enough to pin the
+ * page to its mapping.
+ */
+void truncate_inode_page(struct address_space *mapping, struct page *page)
+{
+ if (page_mapped(page)) {
+ unmap_mapping_range(mapping,
+ (loff_t)page->index << PAGE_CACHE_SHIFT,
+ PAGE_CACHE_SIZE, 0);
+ }
+ truncate_complete_page(mapping, page);
+}
+
/**
* truncate_inode_pages - truncate range of pages specified by start & end byte offsets
* @mapping: mapping to truncate
@@ -196,12 +216,7 @@ void truncate_inode_pages_range(struct a
unlock_page(page);
continue;
}
- if (page_mapped(page)) {
- unmap_mapping_range(mapping,
- (loff_t)page_index<<PAGE_CACHE_SHIFT,
- PAGE_CACHE_SIZE, 0);
- }
- truncate_complete_page(mapping, page);
+ truncate_inode_page(mapping, page);
unlock_page(page);
}
pagevec_release(&pvec);
@@ -238,15 +253,10 @@ void truncate_inode_pages_range(struct a
break;
lock_page(page);
wait_on_page_writeback(page);
- if (page_mapped(page)) {
- unmap_mapping_range(mapping,
- (loff_t)page->index<<PAGE_CACHE_SHIFT,
- PAGE_CACHE_SIZE, 0);
- }
+ truncate_inode_page(mapping, page);
if (page->index > next)
next = page->index;
next++;
- truncate_complete_page(mapping, page);
unlock_page(page);
}
pagevec_release(&pvec);
--- linux.orig/include/linux/mm.h
+++ linux/include/linux/mm.h
@@ -808,6 +808,8 @@ static inline void unmap_shared_mapping_
extern int vmtruncate(struct inode * inode, loff_t offset);
extern int vmtruncate_range(struct inode * inode, loff_t offset, loff_t end);

+void truncate_inode_page(struct address_space *mapping, struct page *page);
+
#ifdef CONFIG_MMU
extern int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long address, int write_access);

\
 
 \ /
  Last update: 2009-06-12 16:03    [W:0.284 / U:0.072 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site