On 09/06/2013 01:16 PM, Weijie Yang wrote:
> To avoid zswap store and reclaim functions called recursively,
> use GFP_NOIO instead of GFP_KERNEL
>
The reason of using GFP_KERNEL in write back path is we want to try our
best to move those pages from zswap to real swap device.
I think it would be better to keep GFP_KERNEL flag but find some other
ways to skip zswap/zswap_frontswap_store() if zswap write back is in
progress.
What I can think of currently is adding a mutex to zswap, take that
mutex when zswap write back happens and check the mutex in
zswap_frontswap_store().
> Signed-off-by: Weijie Yang <weijie.yang@xxxxxxxxxxx>
> ---
> mm/zswap.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/mm/zswap.c b/mm/zswap.c
> index cc40e6a..3d05ed8 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -427,7 +427,7 @@ static int zswap_get_swap_cache_page(swp_entry_t entry,
> * Get a new page to read into from swap.
> */
> if (!new_page) {
> - new_page = alloc_page(GFP_KERNEL);
> + new_page = alloc_page(GFP_NOIO);
> if (!new_page)
> break; /* Out of memory */
> }
> @@ -435,7 +435,7 @@ static int zswap_get_swap_cache_page(swp_entry_t entry,
> /*
> * call radix_tree_preload() while we can wait.
> */
> - err = radix_tree_preload(GFP_KERNEL);
> + err = radix_tree_preload(GFP_NOIO);
> if (err)
> break;
>
> @@ -636,7 +636,7 @@ static int zswap_frontswap_store(unsigned type, pgoff_t offset,
> }
>
> /* allocate entry */
> - entry = zswap_entry_cache_alloc(GFP_KERNEL);
> + entry = zswap_entry_cache_alloc(GFP_NOIO);
> if (!entry) {
> zswap_reject_kmemcache_fail++;
> ret = -ENOMEM;
>
--
Regards,
-Bob
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