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Message-ID: <20120727150823.GD3033@herton-Z68MA-D2H-B3>
Date: Fri, 27 Jul 2012 12:08:24 -0300
From: Herton Ronaldo Krzesinski <herton.krzesinski@...onical.com>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: linux-kernel@...r.kernel.org, stable@...r.kernel.org,
torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
alan@...rguk.ukuu.org.uk, Mel Gorman <mgorman@...e.de>,
Miao Xie <miaox@...fujitsu.com>,
David Rientjes <rientjes@...gle.com>,
Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Christoph Lameter <cl@...ux.com>
Subject: Re: [ 39/40] cpuset: mm: reduce large amounts of memory barrier
related damage v3
On Thu, Jul 26, 2012 at 02:29:57PM -0700, Greg Kroah-Hartman wrote:
> From: Greg KH <gregkh@...uxfoundation.org>
>
> 3.0-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Mel Gorman <mgorman@...e.de>
>
> commit cc9a6c8776615f9c194ccf0b63a0aa5628235545 upstream.
>
> Stable note: Not tracked in Bugzilla. [get|put]_mems_allowed() is extremely
> expensive and severely impacted page allocator performance. This
> is part of a series of patches that reduce page allocator overhead.
>
> Commit c0ff7453bb5c ("cpuset,mm: fix no node to alloc memory when
> changing cpuset's mems") wins a super prize for the largest number of
> memory barriers entered into fast paths for one commit.
>
> [get|put]_mems_allowed is incredibly heavy with pairs of full memory
> barriers inserted into a number of hot paths. This was detected while
> investigating at large page allocator slowdown introduced some time
> after 2.6.32. The largest portion of this overhead was shown by
> oprofile to be at an mfence introduced by this commit into the page
> allocator hot path.
>
> For extra style points, the commit introduced the use of yield() in an
> implementation of what looks like a spinning mutex.
>
> This patch replaces the full memory barriers on both read and write
> sides with a sequence counter with just read barriers on the fast path
> side. This is much cheaper on some architectures, including x86. The
> main bulk of the patch is the retry logic if the nodemask changes in a
> manner that can cause a false failure.
>
> While updating the nodemask, a check is made to see if a false failure
> is a risk. If it is, the sequence number gets bumped and parallel
> allocators will briefly stall while the nodemask update takes place.
>
> In a page fault test microbenchmark, oprofile samples from
> __alloc_pages_nodemask went from 4.53% of all samples to 1.15%. The
> actual results were
>
> 3.3.0-rc3 3.3.0-rc3
> rc3-vanilla nobarrier-v2r1
> Clients 1 UserTime 0.07 ( 0.00%) 0.08 (-14.19%)
> Clients 2 UserTime 0.07 ( 0.00%) 0.07 ( 2.72%)
> Clients 4 UserTime 0.08 ( 0.00%) 0.07 ( 3.29%)
> Clients 1 SysTime 0.70 ( 0.00%) 0.65 ( 6.65%)
> Clients 2 SysTime 0.85 ( 0.00%) 0.82 ( 3.65%)
> Clients 4 SysTime 1.41 ( 0.00%) 1.41 ( 0.32%)
> Clients 1 WallTime 0.77 ( 0.00%) 0.74 ( 4.19%)
> Clients 2 WallTime 0.47 ( 0.00%) 0.45 ( 3.73%)
> Clients 4 WallTime 0.38 ( 0.00%) 0.37 ( 1.58%)
> Clients 1 Flt/sec/cpu 497620.28 ( 0.00%) 520294.53 ( 4.56%)
> Clients 2 Flt/sec/cpu 414639.05 ( 0.00%) 429882.01 ( 3.68%)
> Clients 4 Flt/sec/cpu 257959.16 ( 0.00%) 258761.48 ( 0.31%)
> Clients 1 Flt/sec 495161.39 ( 0.00%) 517292.87 ( 4.47%)
> Clients 2 Flt/sec 820325.95 ( 0.00%) 850289.77 ( 3.65%)
> Clients 4 Flt/sec 1020068.93 ( 0.00%) 1022674.06 ( 0.26%)
> MMTests Statistics: duration
> Sys Time Running Test (seconds) 135.68 132.17
> User+Sys Time Running Test (seconds) 164.2 160.13
> Total Elapsed Time (seconds) 123.46 120.87
>
> The overall improvement is small but the System CPU time is much
> improved and roughly in correlation to what oprofile reported (these
> performance figures are without profiling so skew is expected). The
> actual number of page faults is noticeably improved.
>
> For benchmarks like kernel builds, the overall benefit is marginal but
> the system CPU time is slightly reduced.
>
> To test the actual bug the commit fixed I opened two terminals. The
> first ran within a cpuset and continually ran a small program that
> faulted 100M of anonymous data. In a second window, the nodemask of the
> cpuset was continually randomised in a loop.
>
> Without the commit, the program would fail every so often (usually
> within 10 seconds) and obviously with the commit everything worked fine.
> With this patch applied, it also worked fine so the fix should be
> functionally equivalent.
>
> Signed-off-by: Mel Gorman <mgorman@...e.de>
> Cc: Miao Xie <miaox@...fujitsu.com>
> Cc: David Rientjes <rientjes@...gle.com>
> Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
> Cc: Christoph Lameter <cl@...ux.com>
> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
> Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
> Signed-off-by: Mel Gorman <mgorman@...e.de>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
>
>
> ---
> include/linux/cpuset.h | 49 ++++++++++++++++++----------------------------
> include/linux/init_task.h | 8 +++++++
> include/linux/sched.h | 2 -
> kernel/cpuset.c | 43 +++++++---------------------------------
> kernel/fork.c | 3 ++
> mm/filemap.c | 11 ++++++----
> mm/hugetlb.c | 15 ++++++++++----
> mm/mempolicy.c | 28 +++++++++++++++++++-------
> mm/page_alloc.c | 33 +++++++++++++++++++++---------
> mm/slab.c | 13 +++++++-----
> mm/slub.c | 35 +++++++++++++++++++++-----------
> mm/vmscan.c | 2 -
> 12 files changed, 133 insertions(+), 109 deletions(-)
>
> --- a/include/linux/cpuset.h
> +++ b/include/linux/cpuset.h
> @@ -89,36 +89,25 @@ extern void rebuild_sched_domains(void);
> extern void cpuset_print_task_mems_allowed(struct task_struct *p);
>
> /*
> - * reading current mems_allowed and mempolicy in the fastpath must protected
> - * by get_mems_allowed()
> + * get_mems_allowed is required when making decisions involving mems_allowed
> + * such as during page allocation. mems_allowed can be updated in parallel
> + * and depending on the new value an operation can fail potentially causing
> + * process failure. A retry loop with get_mems_allowed and put_mems_allowed
> + * prevents these artificial failures.
> */
> -static inline void get_mems_allowed(void)
> +static inline unsigned int get_mems_allowed(void)
> {
> - current->mems_allowed_change_disable++;
> + return read_seqcount_begin(¤t->mems_allowed_seq);
> +}
>
> - /*
> - * ensure that reading mems_allowed and mempolicy happens after the
> - * update of ->mems_allowed_change_disable.
> - *
> - * the write-side task finds ->mems_allowed_change_disable is not 0,
> - * and knows the read-side task is reading mems_allowed or mempolicy,
> - * so it will clear old bits lazily.
> - */
> - smp_mb();
> -}
> -
> -static inline void put_mems_allowed(void)
> -{
> - /*
> - * ensure that reading mems_allowed and mempolicy before reducing
> - * mems_allowed_change_disable.
> - *
> - * the write-side task will know that the read-side task is still
> - * reading mems_allowed or mempolicy, don't clears old bits in the
> - * nodemask.
> - */
> - smp_mb();
> - --ACCESS_ONCE(current->mems_allowed_change_disable);
> +/*
> + * If this returns false, the operation that took place after get_mems_allowed
> + * may have failed. It is up to the caller to retry the operation if
> + * appropriate.
> + */
> +static inline bool put_mems_allowed(unsigned int seq)
> +{
> + return !read_seqcount_retry(¤t->mems_allowed_seq, seq);
> }
>
> static inline void set_mems_allowed(nodemask_t nodemask)
> @@ -234,12 +223,14 @@ static inline void set_mems_allowed(node
> {
> }
>
> -static inline void get_mems_allowed(void)
> +static inline unsigned int get_mems_allowed(void)
> {
> + return 0;
> }
>
> -static inline void put_mems_allowed(void)
> +static inline bool put_mems_allowed(unsigned int seq)
> {
> + return true;
> }
>
> #endif /* !CONFIG_CPUSETS */
> --- a/include/linux/init_task.h
> +++ b/include/linux/init_task.h
> @@ -30,6 +30,13 @@ extern struct fs_struct init_fs;
> #define INIT_THREADGROUP_FORK_LOCK(sig)
> #endif
>
> +#ifdef CONFIG_CPUSETS
> +#define INIT_CPUSET_SEQ \
> + .mems_allowed_seq = SEQCNT_ZERO,
> +#else
> +#define INIT_CPUSET_SEQ
> +#endif
> +
> #define INIT_SIGNALS(sig) { \
> .nr_threads = 1, \
> .wait_chldexit = __WAIT_QUEUE_HEAD_INITIALIZER(sig.wait_chldexit),\
> @@ -193,6 +200,7 @@ extern struct cred init_cred;
> INIT_FTRACE_GRAPH \
> INIT_TRACE_RECURSION \
> INIT_TASK_RCU_PREEMPT(tsk) \
> + INIT_CPUSET_SEQ \
> }
>
>
> --- a/include/linux/sched.h
> +++ b/include/linux/sched.h
> @@ -1484,7 +1484,7 @@ struct task_struct {
> #endif
> #ifdef CONFIG_CPUSETS
> nodemask_t mems_allowed; /* Protected by alloc_lock */
> - int mems_allowed_change_disable;
> + seqcount_t mems_allowed_seq; /* Seqence no to catch updates */
> int cpuset_mem_spread_rotor;
> int cpuset_slab_spread_rotor;
> #endif
> --- a/kernel/cpuset.c
> +++ b/kernel/cpuset.c
> @@ -964,7 +964,6 @@ static void cpuset_change_task_nodemask(
> {
> bool need_loop;
>
> -repeat:
> /*
> * Allow tasks that have access to memory reserves because they have
> * been OOM killed to get memory anywhere.
> @@ -983,45 +982,19 @@ repeat:
> */
> need_loop = task_has_mempolicy(tsk) ||
> !nodes_intersects(*newmems, tsk->mems_allowed);
> - nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
> - mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
>
> - /*
> - * ensure checking ->mems_allowed_change_disable after setting all new
> - * allowed nodes.
> - *
> - * the read-side task can see an nodemask with new allowed nodes and
> - * old allowed nodes. and if it allocates page when cpuset clears newly
> - * disallowed ones continuous, it can see the new allowed bits.
> - *
> - * And if setting all new allowed nodes is after the checking, setting
> - * all new allowed nodes and clearing newly disallowed ones will be done
> - * continuous, and the read-side task may find no node to alloc page.
> - */
> - smp_mb();
> -
> - /*
> - * Allocation of memory is very fast, we needn't sleep when waiting
> - * for the read-side.
> - */
> - while (need_loop && ACCESS_ONCE(tsk->mems_allowed_change_disable)) {
> - task_unlock(tsk);
> - if (!task_curr(tsk))
> - yield();
> - goto repeat;
> - }
> + if (need_loop)
> + write_seqcount_begin(&tsk->mems_allowed_seq);
>
> - /*
> - * ensure checking ->mems_allowed_change_disable before clearing all new
> - * disallowed nodes.
> - *
> - * if clearing newly disallowed bits before the checking, the read-side
> - * task may find no node to alloc page.
> - */
> - smp_mb();
> + nodes_or(tsk->mems_allowed, tsk->mems_allowed, *newmems);
> + mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP1);
>
> mpol_rebind_task(tsk, newmems, MPOL_REBIND_STEP2);
> tsk->mems_allowed = *newmems;
> +
> + if (need_loop)
> + write_seqcount_end(&tsk->mems_allowed_seq);
> +
> task_unlock(tsk);
> }
>
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -985,6 +985,9 @@ static int copy_signal(unsigned long clo
> #ifdef CONFIG_CGROUPS
> init_rwsem(&sig->threadgroup_fork_lock);
> #endif
> +#ifdef CONFIG_CPUSETS
> + seqcount_init(&tsk->mems_allowed_seq);
> +#endif
>
> sig->oom_adj = current->signal->oom_adj;
> sig->oom_score_adj = current->signal->oom_score_adj;
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -516,10 +516,13 @@ struct page *__page_cache_alloc(gfp_t gf
> struct page *page;
>
> if (cpuset_do_page_mem_spread()) {
> - get_mems_allowed();
> - n = cpuset_mem_spread_node();
> - page = alloc_pages_exact_node(n, gfp, 0);
> - put_mems_allowed();
> + unsigned int cpuset_mems_cookie;
> + do {
> + cpuset_mems_cookie = get_mems_allowed();
> + n = cpuset_mem_spread_node();
> + page = alloc_pages_exact_node(n, gfp, 0);
> + } while (!put_mems_allowed(cpuset_mems_cookie) && !page);
> +
> return page;
> }
> return alloc_pages(gfp, 0);
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -454,14 +454,16 @@ static struct page *dequeue_huge_page_vm
> struct vm_area_struct *vma,
> unsigned long address, int avoid_reserve)
> {
> - struct page *page = NULL;
> + struct page *page;
> struct mempolicy *mpol;
> nodemask_t *nodemask;
> struct zonelist *zonelist;
> struct zone *zone;
> struct zoneref *z;
> + unsigned int cpuset_mems_cookie;
>
> - get_mems_allowed();
> +retry_cpuset:
> + cpuset_mems_cookie = get_mems_allowed();
> zonelist = huge_zonelist(vma, address,
> htlb_alloc_mask, &mpol, &nodemask);
> /*
> @@ -488,10 +490,15 @@ static struct page *dequeue_huge_page_vm
> }
> }
> }
> -err:
> +
> mpol_cond_put(mpol);
> - put_mems_allowed();
> + if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
> + goto retry_cpuset;
> return page;
> +
> +err:
> + mpol_cond_put(mpol);
> + return NULL;
> }
>
> static void update_and_free_page(struct hstate *h, struct page *page)
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -1810,18 +1810,24 @@ struct page *
> alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
> unsigned long addr, int node)
> {
> - struct mempolicy *pol = get_vma_policy(current, vma, addr);
> + struct mempolicy *pol;
> struct zonelist *zl;
> struct page *page;
> + unsigned int cpuset_mems_cookie;
> +
> +retry_cpuset:
> + pol = get_vma_policy(current, vma, addr);
> + cpuset_mems_cookie = get_mems_allowed();
>
> - get_mems_allowed();
> if (unlikely(pol->mode == MPOL_INTERLEAVE)) {
> unsigned nid;
>
> nid = interleave_nid(pol, vma, addr, PAGE_SHIFT + order);
> mpol_cond_put(pol);
> page = alloc_page_interleave(gfp, order, nid);
> - put_mems_allowed();
> + if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
> + goto retry_cpuset;
> +
> return page;
> }
> zl = policy_zonelist(gfp, pol, node);
> @@ -1832,7 +1838,8 @@ alloc_pages_vma(gfp_t gfp, int order, st
> struct page *page = __alloc_pages_nodemask(gfp, order,
> zl, policy_nodemask(gfp, pol));
> __mpol_put(pol);
> - put_mems_allowed();
> + if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
> + goto retry_cpuset;
> return page;
> }
> /*
> @@ -1840,7 +1847,8 @@ alloc_pages_vma(gfp_t gfp, int order, st
> */
> page = __alloc_pages_nodemask(gfp, order, zl,
> policy_nodemask(gfp, pol));
> - put_mems_allowed();
> + if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
> + goto retry_cpuset;
> return page;
> }
>
> @@ -1867,11 +1875,14 @@ struct page *alloc_pages_current(gfp_t g
> {
> struct mempolicy *pol = current->mempolicy;
> struct page *page;
> + unsigned int cpuset_mems_cookie;
>
> if (!pol || in_interrupt() || (gfp & __GFP_THISNODE))
> pol = &default_policy;
>
> - get_mems_allowed();
> +retry_cpuset:
> + cpuset_mems_cookie = get_mems_allowed();
> +
> /*
> * No reference counting needed for current->mempolicy
> * nor system default_policy
> @@ -1882,7 +1893,10 @@ struct page *alloc_pages_current(gfp_t g
> page = __alloc_pages_nodemask(gfp, order,
> policy_zonelist(gfp, pol, numa_node_id()),
> policy_nodemask(gfp, pol));
> - put_mems_allowed();
> +
> + if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
> + goto retry_cpuset;
> +
> return page;
> }
> EXPORT_SYMBOL(alloc_pages_current);
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2293,8 +2293,9 @@ __alloc_pages_nodemask(gfp_t gfp_mask, u
> {
> enum zone_type high_zoneidx = gfp_zone(gfp_mask);
> struct zone *preferred_zone;
> - struct page *page;
> + struct page *page = NULL;
> int migratetype = allocflags_to_migratetype(gfp_mask);
> + unsigned int cpuset_mems_cookie;
>
> gfp_mask &= gfp_allowed_mask;
>
> @@ -2313,15 +2314,15 @@ __alloc_pages_nodemask(gfp_t gfp_mask, u
> if (unlikely(!zonelist->_zonerefs->zone))
> return NULL;
>
> - get_mems_allowed();
> +retry_cpuset:
> + cpuset_mems_cookie = get_mems_allowed();
> +
> /* The preferred zone is used for statistics later */
> first_zones_zonelist(zonelist, high_zoneidx,
> nodemask ? : &cpuset_current_mems_allowed,
> &preferred_zone);
> - if (!preferred_zone) {
> - put_mems_allowed();
> - return NULL;
> - }
> + if (!preferred_zone)
> + goto out;
>
> /* First allocation attempt */
> page = get_page_from_freelist(gfp_mask|__GFP_HARDWALL, nodemask, order,
> @@ -2331,9 +2332,19 @@ __alloc_pages_nodemask(gfp_t gfp_mask, u
> page = __alloc_pages_slowpath(gfp_mask, order,
> zonelist, high_zoneidx, nodemask,
> preferred_zone, migratetype);
> - put_mems_allowed();
>
> trace_mm_page_alloc(page, order, gfp_mask, migratetype);
> +
> +out:
> + /*
> + * When updating a task's mems_allowed, it is possible to race with
> + * parallel threads in such a way that an allocation can fail while
> + * the mask is being updated. If a page allocation is about to fail,
> + * check if the cpuset changed during allocation and if so, retry.
> + */
> + if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !page))
> + goto retry_cpuset;
> +
> return page;
> }
> EXPORT_SYMBOL(__alloc_pages_nodemask);
> @@ -2557,13 +2568,15 @@ void si_meminfo_node(struct sysinfo *val
> bool skip_free_areas_node(unsigned int flags, int nid)
> {
> bool ret = false;
> + unsigned int cpuset_mems_cookie;
>
> if (!(flags & SHOW_MEM_FILTER_NODES))
> goto out;
>
> - get_mems_allowed();
> - ret = !node_isset(nid, cpuset_current_mems_allowed);
> - put_mems_allowed();
> + do {
> + cpuset_mems_cookie = get_mems_allowed();
> + ret = !node_isset(nid, cpuset_current_mems_allowed);
> + } while (!put_mems_allowed(cpuset_mems_cookie));
> out:
> return ret;
> }
> --- a/mm/slab.c
> +++ b/mm/slab.c
> @@ -3218,12 +3218,10 @@ static void *alternate_node_alloc(struct
> if (in_interrupt() || (flags & __GFP_THISNODE))
> return NULL;
> nid_alloc = nid_here = numa_mem_id();
> - get_mems_allowed();
> if (cpuset_do_slab_mem_spread() && (cachep->flags & SLAB_MEM_SPREAD))
> nid_alloc = cpuset_slab_spread_node();
> else if (current->mempolicy)
> nid_alloc = slab_node(current->mempolicy);
> - put_mems_allowed();
> if (nid_alloc != nid_here)
> return ____cache_alloc_node(cachep, flags, nid_alloc);
> return NULL;
> @@ -3246,14 +3244,17 @@ static void *fallback_alloc(struct kmem_
> enum zone_type high_zoneidx = gfp_zone(flags);
> void *obj = NULL;
> int nid;
> + unsigned int cpuset_mems_cookie;
>
> if (flags & __GFP_THISNODE)
> return NULL;
>
> - get_mems_allowed();
> - zonelist = node_zonelist(slab_node(current->mempolicy), flags);
> local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);
>
> +retry_cpuset:
> + cpuset_mems_cookie = get_mems_allowed();
> + zonelist = node_zonelist(slab_node(current->mempolicy), flags);
> +
> retry:
> /*
> * Look through allowed nodes for objects available
> @@ -3306,7 +3307,9 @@ retry:
> }
> }
> }
> - put_mems_allowed();
> +
> + if (unlikely(!put_mems_allowed(cpuset_mems_cookie) && !obj))
> + goto retry_cpuset;
> return obj;
> }
>
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -1457,6 +1457,7 @@ static struct page *get_any_partial(stru
> struct zone *zone;
> enum zone_type high_zoneidx = gfp_zone(flags);
> struct page *page;
> + unsigned int cpuset_mems_cookie;
>
> /*
> * The defrag ratio allows a configuration of the tradeoffs between
> @@ -1480,22 +1481,32 @@ static struct page *get_any_partial(stru
> get_cycles() % 1024 > s->remote_node_defrag_ratio)
> return NULL;
>
> - get_mems_allowed();
> - zonelist = node_zonelist(slab_node(current->mempolicy), flags);
> - for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
> - struct kmem_cache_node *n;
> + do {
> + cpuset_mems_cookie = get_mems_allowed();
> + zonelist = node_zonelist(slab_node(current->mempolicy), flags);
> + for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
> + struct kmem_cache_node *n;
>
> - n = get_node(s, zone_to_nid(zone));
> + n = get_node(s, zone_to_nid(zone));
>
> - if (n && cpuset_zone_allowed_hardwall(zone, flags) &&
> - n->nr_partial > s->min_partial) {
> - page = get_partial_node(n);
> - if (page) {
> - put_mems_allowed();
> - return page;
> + if (n && cpuset_zone_allowed_hardwall(zone, flags) &&
> + n->nr_partial > s->min_partial) {
> + page = get_partial_node(n);
> + if (page) {
> + /*
> + * Return the object even if
> + * put_mems_allowed indicated that
> + * the cpuset mems_allowed was
> + * updated in parallel. It's a
> + * harmless race between the alloc
> + * and the cpuset update.
> + */
> + put_mems_allowed(cpuset_mems_cookie);
> + return page;
> + }
> }
> }
> - }
> + } while (!put_mems_allowed(cpuset_mems_cookie));
> put_mems_allowed();
This doesn't build on 3.0, the backport left the stray put_mems_allowed
above:
linux-stable/mm/slub.c: In function 'get_any_partial':
linux-stable/mm/slub.c:1510:2: error: too few arguments to function 'put_mems_allowed'
linux-stable/include/linux/cpuset.h:108:20: note: declared here
> #endif
> return NULL;
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2251,7 +2251,6 @@ static unsigned long do_try_to_free_page
> unsigned long writeback_threshold;
> bool aborted_reclaim;
>
> - get_mems_allowed();
> delayacct_freepages_start();
>
> if (scanning_global_lru(sc))
> @@ -2314,7 +2313,6 @@ static unsigned long do_try_to_free_page
>
> out:
> delayacct_freepages_end();
> - put_mems_allowed();
>
> if (sc->nr_reclaimed)
> return sc->nr_reclaimed;
>
>
> --
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>
--
[]'s
Herton
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