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

[Will Huck]

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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