linux-stable.git/drivers/staging/zcache, branch v3.2

Merge branch 'staging-next' into Linux 3.1

2011-10-25T07:18:11+00:00

This was done to resolve a conflict in the
drivers/staging/comedi/drivers/ni_labpc.c file that resolved a build
bugfix in Linus's tree with a "better" bugfix that was in the
staging-next tree that resolved the issue in a more complete manner.

Signed-off-by: Greg Kroah-Hartman

staging: zcache: remove zcache_direct_reclaim_lock

2011-10-17T22:24:11+00:00

zcache_do_preload() currently does a spin_trylock() on the
zcache_direct_reclaim_lock. Holding this lock intends to prevent
shrink_zcache_memory() from evicting zbud pages as a result
of a preload.

However, it also prevents two threads from
executing zcache_do_preload() at the same time.  The first
thread will obtain the lock and the second thread's spin_trylock()
will fail (an aborted preload) causing the page to be either lost
(cleancache) or pushed out to the swap device (frontswap). It
also doesn't ensure that the call to shrink_zcache_memory() is
on the same thread as the call to zcache_do_preload().

Additional, there is no need for this mechanism because all
zcache_do_preload() calls that come down from cleancache already
have PF_MEMALLOC set in the process flags which prevents
direct reclaim in the memory manager. If the zcache_do_preload()
call is done from the frontswap path, we _want_ reclaim to be
done (which it isn't right now).

This patch removes the zcache_direct_reclaim_lock and related
statistics in zcache.

Based on v3.1-rc8

Signed-off-by: Seth Jennings 
Reviewed-by: Dave Hansen 
Acked-by: Dan Magenheimer 
Signed-off-by: Greg Kroah-Hartman

staging: zcache: reduce tmem bucket lock contention

2011-10-12T15:29:03+00:00

tmem uses hash buckets each with their own rbtree and lock to
quickly lookup tmem objects.  tmem has TMEM_HASH_BUCKETS (256)
buckets per pool.  However, because of the way the tmem_oid is
generated for frontswap pages, only 16 unique tmem_oids are being
generated, resulting in only 16 of the 256 buckets being used.
This cause high lock contention for the per bucket locks.

This patch changes SWIZ_BITS to include more bits of the offset.
The result is that all 256 hash buckets are potentially used resulting in a
95% drop in hash bucket lock contention.

Signed-off-by: Seth Jennings 
Acked-by: Dan Magenheimer 
Signed-off-by: Greg Kroah-Hartman

staging: zcache: fix crash on cpu remove

2011-10-11T16:02:49+00:00

In the case that a cpu is taken offline before zcache_do_preload() is
ever called on the cpu, the per-cpu zcache_preloads structure will
be uninitialized.  In the CPU_DEAD case for zcache_cpu_notifier(),
kp->obj is not checked before calling kmem_cache_free() on it.
If it is NULL, a crash results.

This patch ensures that both kp->obj and kp->page are not NULL before
calling the respective free functions. In practice, just checking
one or the other should be sufficient since they are assigned together
in zcache_do_preload(), but I check both for safety.

Signed-off-by: Seth Jennings 
Acked-by: Dave Hansen 
Signed-off-by: Greg Kroah-Hartman

staging: zcache: fix cleancache crash

2011-09-20T21:17:13+00:00

After commit c5f5c4db3938 ("staging: zcache: fix crash on high memory
swap") cleancache crashes on the first successful get.  This was caused
by a remaining virt_to_page() call in zcache_pampd_get_data_and_free()
that only gets run in the cleancache path.

The patch converts the virt_to_page() to struct page casting like was
done for other instances in c5f5c4db3938.

Signed-off-by: Seth Jennings 
Tested-By: Valdis Kletnieks 
Acked-by: Dan Magenheimer 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Linus Torvalds

Merge 3.1-rc4 into staging-next

2011-08-29T15:47:46+00:00

This resolves a conflict with:
	drivers/staging/brcm80211/brcmsmac/types.h

Signed-off-by: Greg Kroah-Hartman

Staging: zcache: signedness bug in tmem_get()

2011-08-23T21:52:20+00:00

"ret" needs to be signed for the error handling to work properly.

Signed-off-by: Dan Carpenter 
Acked-by: Dan Magenheimer 
Signed-off-by: Greg Kroah-Hartman

staging: zcache: fix crash on high memory swap

2011-08-23T21:52:20+00:00

zcache_put_page() was modified to pass page_address(page) instead of the
actual page structure. In combination with the function signature changes
to tmem_put() and zcache_pampd_create(), zcache_pampd_create() tries to
(re)derive the page structure from the virtual address.  However, if the
original page is a high memory page (or any unmapped page), this
virt_to_page() fails because the page_address() in zcache_put_page()
returned NULL.

This patch changes zcache_put_page() and zcache_get_page() to pass
the page structure instead of the page's virtual address, which
may or may not exist.

Signed-off-by: Seth Jennings 
Acked-by: Dan Magenheimer 
Signed-off-by: Greg Kroah-Hartman

staging: zcache: fix typos

2011-08-23T21:49:33+00:00

The patch fixes two typos in zcache-main.c

Signed-off-by: Seth Jennings 
Acked-by: Dan Magenheimer 
Signed-off-by: Greg Kroah-Hartman

staging: zcache: fix possible sleep under lock

2011-08-23T21:49:33+00:00

zcache_new_pool() calls kmalloc() with GFP_KERNEL which has
__GFP_WAIT set.  However, zcache_new_pool() gets called on
a stack that holds the swap_lock spinlock, leading to a
possible sleep-with-lock situation. The lock is obtained
in enable_swap_info().

The patch replaces GFP_KERNEL with GFP_ATOMIC.

v2: replace with GFP_ATOMIC, not GFP_IOFS

Signed-off-by: Seth Jennings 
Acked-by: Dan Magenheimer 
Signed-off-by: Greg Kroah-Hartman