Re: Inactive memory keep growing and how to release it?

From: Will Huck
Date: Fri Mar 08 2013 - 21:14:29 EST


Cc experts. Hugh, Johannes,

On 03/04/2013 08:21 PM, Lenky Gao wrote:
2013/3/4 Zlatko Calusic <zlatko.calusic@xxxxxxxx>:
The drop_caches mechanism doesn't free dirty page cache pages. And your bash
script is creating a lot of dirty pages. Run it like this and see if it
helps your case:

sync; echo 3 > /proc/sys/vm/drop_caches
Thanks for your advice.

The inactive memory still cannot be reclaimed after i execute the sync command:

# cat /proc/meminfo | grep Inactive\(file\);
Inactive(file): 882824 kB
# sync;
# echo 3 > /proc/sys/vm/drop_caches
# cat /proc/meminfo | grep Inactive\(file\);
Inactive(file): 777664 kB

I find these page becomes orphaned in this function, but do not understand why:

/*
* If truncate cannot remove the fs-private metadata from the page, the page
* becomes orphaned. It will be left on the LRU and may even be mapped into
* user pagetables if we're racing with filemap_fault().
*
* We need to bale out if page->mapping is no longer equal to the original
* mapping. This happens a) when the VM reclaimed the page while we waited on
* its lock, b) when a concurrent invalidate_mapping_pages got there first and
* c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
*/
static int
truncate_complete_page(struct address_space *mapping, struct page *page)
{
...

My file system type is ext3, mounted with the opteion data=journal and
it is easy to reproduce.



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