Hello,

On Thu, Aug 23, 2012 at 04:31:43PM -0400, Naoya Horiguchi wrote:

On Thu, Aug 23, 2012 at 05:11:25PM +0800, Fengguang Wu wrote:

quoted

On Wed, Aug 22, 2012 at 11:17:35AM -0400, Naoya Horiguchi wrote:

...

quoted

quoted

diff --git v3.6-rc1.orig/fs/inode.c v3.6-rc1/fs/inode.c
index ac8d904..8742397 100644
--- v3.6-rc1.orig/fs/inode.c
+++ v3.6-rc1/fs/inode.c

@@ -717,6 +717,15 @@ void prune_icache_sb(struct super_block *sb, int nr_to_scan)
 		}
 
 		/*
+		 * Keep inode caches on memory for user processes to certainly
+		 * be aware of memory errors.
+		 */
+		if (unlikely(mapping_hwpoison(inode->i_mapping))) {
+			spin_unlock(&inode->i_lock);
+			continue;
+		}

That chunk prevents reclaiming all the cached pages. However the intention
is only to keep the struct inode together with the hwpoison bit?

Yes, we can not reclaim pagecaches from shrink_slab(), but we can do from
shrink_zone(). So it shouldn't happen that cached pages on hwpoisoned file
remain for long under high memory pressure.

I might lose your point. Are you suggesting this chunk should come after
if (inode_has_buffers(inode) || inode->i_data.nrpages) { ... } block,
aren't you?  I think that's right, so I'll try and test it this weekend.

quoted

quoted

+		/*
 		 * Referenced or dirty inodes are still in use. Give them
 		 * another pass through the LRU as we canot reclaim them now.
 		 */

@@ -1405,6 +1414,9 @@ static void iput_final(struct inode *inode)
 		inode->i_state &= ~I_WILL_FREE;
 	}
 
+	if (unlikely(mapping_hwpoison(inode->i_mapping) && drop))
+		mapping_clear_hwpoison(inode->i_mapping);

Is that clear necessary? Because the bit will be gone with the inode
struct: it's going to be de-allocated anyway.

With the chunk in prune_icache_sb() we keep the inode struct with
AS_HWPOISON set on memory, so in order to remove it, we need explicitly
clear the bit.
Without this clear, the inode remains until system reboot.

And again, you are right here. Without this clear, this inode will be
cleared in destroy_inode().

Thanks,
Naoya

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