diff mbox series

[v2,1/4] mm/page_alloc: fix non cma alloc context

Message ID 1595220978-9890-1-git-send-email-iamjoonsoo.kim@lge.com (mailing list archive)
State New, archived
Headers show
Series [v2,1/4] mm/page_alloc: fix non cma alloc context | expand

Commit Message

Joonsoo Kim July 20, 2020, 4:56 a.m. UTC 
From: Joonsoo Kim <iamjoonsoo.kim@lge.com>

Currently, preventing cma area in page allocation is implemented by using
current_gfp_context(). However, there are two problems of this
implementation.

First, this doesn't work for allocation fastpath. In the fastpath,
original gfp_mask is used since current_gfp_context() is introduced in
order to control reclaim and it is on slowpath.
Second, clearing __GFP_MOVABLE has a side effect to exclude the memory
on the ZONE_MOVABLE for allocation target.

To fix these problems, this patch changes the implementation to exclude
cma area in page allocation. Main point of this change is using the
alloc_flags. alloc_flags is mainly used to control allocation so it fits
for excluding cma area in allocation.

Fixes: d7fefcc8de91 (mm/cma: add PF flag to force non cma alloc)
Cc: <stable@vger.kernel.org>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
---
 include/linux/sched/mm.h |  8 +-------
 mm/page_alloc.c          | 37 ++++++++++++++++++++++++-------------
 2 files changed, 25 insertions(+), 20 deletions(-)

Comments

Andrew Morton July 20, 2020, 11:16 p.m. UTC | #1 
On Mon, 20 Jul 2020 13:56:15 +0900 js1304@gmail.com wrote:

> Currently, preventing cma area in page allocation is implemented by using
> current_gfp_context(). However, there are two problems of this
> implementation.
> 
> First, this doesn't work for allocation fastpath. In the fastpath,
> original gfp_mask is used since current_gfp_context() is introduced in
> order to control reclaim and it is on slowpath.
> Second, clearing __GFP_MOVABLE has a side effect to exclude the memory
> on the ZONE_MOVABLE for allocation target.
> 
> To fix these problems, this patch changes the implementation to exclude
> cma area in page allocation. Main point of this change is using the
> alloc_flags. alloc_flags is mainly used to control allocation so it fits
> for excluding cma area in allocation.

What are the end user visible runtime effects of this change?

This is pretty much essential information when proposing a -stable
backport.
Andrew Morton July 20, 2020, 11:23 p.m. UTC | #2 
On Mon, 20 Jul 2020 13:56:15 +0900 js1304@gmail.com wrote:

> Currently, preventing cma area in page allocation is implemented by using
> current_gfp_context(). However, there are two problems of this
> implementation.
> 
> First, this doesn't work for allocation fastpath. In the fastpath,
> original gfp_mask is used since current_gfp_context() is introduced in
> order to control reclaim and it is on slowpath.
> Second, clearing __GFP_MOVABLE has a side effect to exclude the memory
> on the ZONE_MOVABLE for allocation target.
> 
> To fix these problems, this patch changes the implementation to exclude
> cma area in page allocation. Main point of this change is using the
> alloc_flags. alloc_flags is mainly used to control allocation so it fits
> for excluding cma area in allocation.
> 
> Fixes: d7fefcc8de91 (mm/cma: add PF flag to force non cma alloc)
> Cc: <stable@vger.kernel.org>

This patch is against linux-next (or -mm) and has a lot of issues
applying to mainline.  If we indeed wish to backport it to -stable, it
should be against mainline, please.
Joonsoo Kim July 21, 2020, 3:33 a.m. UTC | #3 
2020년 7월 21일 (화) 오전 8:23, Andrew Morton <akpm@linux-foundation.org>님이 작성:
>
> On Mon, 20 Jul 2020 13:56:15 +0900 js1304@gmail.com wrote:
>
> > Currently, preventing cma area in page allocation is implemented by using
> > current_gfp_context(). However, there are two problems of this
> > implementation.
> >
> > First, this doesn't work for allocation fastpath. In the fastpath,
> > original gfp_mask is used since current_gfp_context() is introduced in
> > order to control reclaim and it is on slowpath.
> > Second, clearing __GFP_MOVABLE has a side effect to exclude the memory
> > on the ZONE_MOVABLE for allocation target.
> >
> > To fix these problems, this patch changes the implementation to exclude
> > cma area in page allocation. Main point of this change is using the
> > alloc_flags. alloc_flags is mainly used to control allocation so it fits
> > for excluding cma area in allocation.
> >
> > Fixes: d7fefcc8de91 (mm/cma: add PF flag to force non cma alloc)
> > Cc: <stable@vger.kernel.org>
>
> This patch is against linux-next (or -mm) and has a lot of issues
> applying to mainline.  If we indeed wish to backport it to -stable, it
> should be against mainline, please.

I sent a revised patch against the mainline a minute ago. Subject and commit
description is updated.

Thanks.
Sasha Levin July 21, 2020, 2:20 p.m. UTC | #4 
Hi

[This is an automated email]

This commit has been processed because it contains a "Fixes:" tag
fixing commit: d7fefcc8de91 ("mm/cma: add PF flag to force non cma alloc").

The bot has tested the following trees: v5.7.9, v5.4.52.

v5.7.9: Failed to apply! Possible dependencies:
    01c0bfe061f30 ("mm: rename gfpflags_to_migratetype to gfp_migratetype for same convention")
    16867664936e3 ("mm,page_alloc,cma: conditionally prefer cma pageblocks for movable allocations")
    3334a45eb9e2b ("mm/page_alloc: use ac->high_zoneidx for classzone_idx")
    63b44f01f1974 ("include/linux/sched/mm.h: optimize current_gfp_context()")
    97a225e69a1f8 ("mm/page_alloc: integrate classzone_idx and high_zoneidx")
    a65064938b815 ("page_alloc: consider highatomic reserve in watermark fast")

v5.4.52: Failed to apply! Possible dependencies:
    01c0bfe061f30 ("mm: rename gfpflags_to_migratetype to gfp_migratetype for same convention")
    16867664936e3 ("mm,page_alloc,cma: conditionally prefer cma pageblocks for movable allocations")
    3334a45eb9e2b ("mm/page_alloc: use ac->high_zoneidx for classzone_idx")
    5644e1fbbfe15 ("mm/vmscan.c: fix data races using kswapd_classzone_idx")
    63b44f01f1974 ("include/linux/sched/mm.h: optimize current_gfp_context()")
    97a225e69a1f8 ("mm/page_alloc: integrate classzone_idx and high_zoneidx")
    a65064938b815 ("page_alloc: consider highatomic reserve in watermark fast")


NOTE: The patch will not be queued to stable trees until it is upstream.

How should we proceed with this patch?
Joonsoo Kim July 23, 2020, 1:53 a.m. UTC | #5 
2020년 7월 21일 (화) 오후 11:24, Sasha Levin <sashal@kernel.org>님이 작성:
>
> Hi
>
> [This is an automated email]
>
> This commit has been processed because it contains a "Fixes:" tag
> fixing commit: d7fefcc8de91 ("mm/cma: add PF flag to force non cma alloc").
>
> The bot has tested the following trees: v5.7.9, v5.4.52.
>
> v5.7.9: Failed to apply! Possible dependencies:
>     01c0bfe061f30 ("mm: rename gfpflags_to_migratetype to gfp_migratetype for same convention")
>     16867664936e3 ("mm,page_alloc,cma: conditionally prefer cma pageblocks for movable allocations")
>     3334a45eb9e2b ("mm/page_alloc: use ac->high_zoneidx for classzone_idx")
>     63b44f01f1974 ("include/linux/sched/mm.h: optimize current_gfp_context()")
>     97a225e69a1f8 ("mm/page_alloc: integrate classzone_idx and high_zoneidx")
>     a65064938b815 ("page_alloc: consider highatomic reserve in watermark fast")
>
> v5.4.52: Failed to apply! Possible dependencies:
>     01c0bfe061f30 ("mm: rename gfpflags_to_migratetype to gfp_migratetype for same convention")
>     16867664936e3 ("mm,page_alloc,cma: conditionally prefer cma pageblocks for movable allocations")
>     3334a45eb9e2b ("mm/page_alloc: use ac->high_zoneidx for classzone_idx")
>     5644e1fbbfe15 ("mm/vmscan.c: fix data races using kswapd_classzone_idx")
>     63b44f01f1974 ("include/linux/sched/mm.h: optimize current_gfp_context()")
>     97a225e69a1f8 ("mm/page_alloc: integrate classzone_idx and high_zoneidx")
>     a65064938b815 ("page_alloc: consider highatomic reserve in watermark fast")
>
>
> NOTE: The patch will not be queued to stable trees until it is upstream.
>
> How should we proceed with this patch?
>

I sent the patch that is against the mainline. Note that the subject is changed.
See the following link please.

http://lkml.kernel.org/r/1595468942-29687-1-git-send-email-iamjoonsoo.kim@lge.com

Thanks.
diff mbox series

Patch

diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index 44ad5b7..6c652ec 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -175,14 +175,12 @@  static inline bool in_vfork(struct task_struct *tsk)
  * Applies per-task gfp context to the given allocation flags.
  * PF_MEMALLOC_NOIO implies GFP_NOIO
  * PF_MEMALLOC_NOFS implies GFP_NOFS
- * PF_MEMALLOC_NOCMA implies no allocation from CMA region.
  */
 static inline gfp_t current_gfp_context(gfp_t flags)
 {
 	unsigned int pflags = READ_ONCE(current->flags);
 
-	if (unlikely(pflags &
-		     (PF_MEMALLOC_NOIO | PF_MEMALLOC_NOFS | PF_MEMALLOC_NOCMA))) {
+	if (unlikely(pflags & (PF_MEMALLOC_NOIO | PF_MEMALLOC_NOFS))) {
 		/*
 		 * NOIO implies both NOIO and NOFS and it is a weaker context
 		 * so always make sure it makes precedence
@@ -191,10 +189,6 @@  static inline gfp_t current_gfp_context(gfp_t flags)
 			flags &= ~(__GFP_IO | __GFP_FS);
 		else if (pflags & PF_MEMALLOC_NOFS)
 			flags &= ~__GFP_FS;
-#ifdef CONFIG_CMA
-		if (pflags & PF_MEMALLOC_NOCMA)
-			flags &= ~__GFP_MOVABLE;
-#endif
 	}
 	return flags;
 }
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 6416d08..b529220 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2791,7 +2791,7 @@  __rmqueue(struct zone *zone, unsigned int order, int migratetype,
 	 * allocating from CMA when over half of the zone's free memory
 	 * is in the CMA area.
 	 */
-	if (migratetype == MIGRATE_MOVABLE &&
+	if (alloc_flags & ALLOC_CMA &&
 	    zone_page_state(zone, NR_FREE_CMA_PAGES) >
 	    zone_page_state(zone, NR_FREE_PAGES) / 2) {
 		page = __rmqueue_cma_fallback(zone, order);
@@ -2802,7 +2802,7 @@  __rmqueue(struct zone *zone, unsigned int order, int migratetype,
 retry:
 	page = __rmqueue_smallest(zone, order, migratetype);
 	if (unlikely(!page)) {
-		if (migratetype == MIGRATE_MOVABLE)
+		if (alloc_flags & ALLOC_CMA)
 			page = __rmqueue_cma_fallback(zone, order);
 
 		if (!page && __rmqueue_fallback(zone, order, migratetype,
@@ -3502,11 +3502,9 @@  static inline long __zone_watermark_unusable_free(struct zone *z,
 	if (likely(!alloc_harder))
 		unusable_free += z->nr_reserved_highatomic;
 
-#ifdef CONFIG_CMA
 	/* If allocation can't use CMA areas don't use free CMA pages */
-	if (!(alloc_flags & ALLOC_CMA))
+	if (IS_ENABLED(CONFIG_CMA) && !(alloc_flags & ALLOC_CMA))
 		unusable_free += zone_page_state(z, NR_FREE_CMA_PAGES);
-#endif
 
 	return unusable_free;
 }
@@ -3693,6 +3691,20 @@  alloc_flags_nofragment(struct zone *zone, gfp_t gfp_mask)
 	return alloc_flags;
 }
 
+static inline unsigned int current_alloc_flags(gfp_t gfp_mask,
+					unsigned int alloc_flags)
+{
+#ifdef CONFIG_CMA
+	unsigned int pflags = current->flags;
+
+	if (!(pflags & PF_MEMALLOC_NOCMA) &&
+		gfp_migratetype(gfp_mask) == MIGRATE_MOVABLE)
+		alloc_flags |= ALLOC_CMA;
+
+#endif
+	return alloc_flags;
+}
+
 /*
  * get_page_from_freelist goes through the zonelist trying to allocate
  * a page.
@@ -4339,10 +4351,8 @@  gfp_to_alloc_flags(gfp_t gfp_mask)
 	} else if (unlikely(rt_task(current)) && !in_interrupt())
 		alloc_flags |= ALLOC_HARDER;
 
-#ifdef CONFIG_CMA
-	if (gfp_migratetype(gfp_mask) == MIGRATE_MOVABLE)
-		alloc_flags |= ALLOC_CMA;
-#endif
+	alloc_flags = current_alloc_flags(gfp_mask, alloc_flags);
+
 	return alloc_flags;
 }
 
@@ -4642,8 +4652,10 @@  __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 		wake_all_kswapds(order, gfp_mask, ac);
 
 	reserve_flags = __gfp_pfmemalloc_flags(gfp_mask);
-	if (reserve_flags)
+	if (reserve_flags) {
 		alloc_flags = reserve_flags;
+		alloc_flags = current_alloc_flags(gfp_mask, alloc_flags);
+	}
 
 	/*
 	 * Reset the nodemask and zonelist iterators if memory policies can be
@@ -4720,7 +4732,7 @@  __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
 
 	/* Avoid allocations with no watermarks from looping endlessly */
 	if (tsk_is_oom_victim(current) &&
-	    (alloc_flags == ALLOC_OOM ||
+	    (alloc_flags & ALLOC_OOM ||
 	     (gfp_mask & __GFP_NOMEMALLOC)))
 		goto nopage;
 
@@ -4808,8 +4820,7 @@  static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order,
 	if (should_fail_alloc_page(gfp_mask, order))
 		return false;
 
-	if (IS_ENABLED(CONFIG_CMA) && ac->migratetype == MIGRATE_MOVABLE)
-		*alloc_flags |= ALLOC_CMA;
+	*alloc_flags = current_alloc_flags(gfp_mask, *alloc_flags);
 
 	return true;
 }