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Date: Mon, 9 Aug 2021 10:44:30 +0800
From: Feng Tang <feng.tang@...el.com>
To: Michal Hocko <mhocko@...e.com>
Cc: linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>,
David Rientjes <rientjes@...gle.com>,
Dave Hansen <dave.hansen@...el.com>,
Ben Widawsky <ben.widawsky@...el.com>,
linux-kernel@...r.kernel.org, linux-api@...r.kernel.org,
Andrea Arcangeli <aarcange@...hat.com>,
Mel Gorman <mgorman@...hsingularity.net>,
Mike Kravetz <mike.kravetz@...cle.com>,
Randy Dunlap <rdunlap@...radead.org>,
Vlastimil Babka <vbabka@...e.cz>,
Andi Kleen <ak@...ux.intel.com>,
Dan Williams <dan.j.williams@...el.com>, ying.huang@...el.com
Subject: Re: [PATCH v7 3/5] mm/hugetlb: add support for mempolicy
MPOL_PREFERRED_MANY
Hi Michal,
Thanks for the review and ACKs to 1/5 and 2/5 patches.
On Fri, Aug 06, 2021 at 03:35:48PM +0200, Michal Hocko wrote:
> On Tue 03-08-21 13:59:20, Feng Tang wrote:
> > From: Ben Widawsky <ben.widawsky@...el.com>
> >
> > Implement the missing huge page allocation functionality while obeying
> > the preferred node semantics. This is similar to the implementation
> > for general page allocation, as it uses a fallback mechanism to try
> > multiple preferred nodes first, and then all other nodes.
> >
> > [akpm: fix compling issue when merging with other hugetlb patch]
> > [Thanks to 0day bot for catching the missing #ifdef CONFIG_NUMA issue]
> > Link: https://lore.kernel.org/r/20200630212517.308045-12-ben.widawsky@intel.com
> > Suggested-by: Michal Hocko <mhocko@...e.com>
> > Signed-off-by: Ben Widawsky <ben.widawsky@...el.com>
> > Co-developed-by: Feng Tang <feng.tang@...el.com>
> > Signed-off-by: Feng Tang <feng.tang@...el.com>
>
> ifdefery is just ugly as hell. One way to get rid of that would be to
> provide a mpol_is_preferred_many() wrapper and hide the CONFIG_NUMA in
> mempolicy.h. I haven't checked but this might help to remove some other
> ifdefery as well.
>
> I especially dislike the label hidden in the ifdef. You can get rid of
> that by checking the page for NULL.
Yes, the 'ifdef's were annoying to me too, and thanks for the suggestions.
Following is the revised patch upon the suggestion.
Thanks,
Feng
-------8<---------------------
>From fc30718c40f02ba5ea73456af49173e66b5032c1 Mon Sep 17 00:00:00 2001
From: Ben Widawsky <ben.widawsky@...el.com>
Date: Thu, 5 Aug 2021 23:01:11 -0400
Subject: [PATCH] mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY
Implement the missing huge page allocation functionality while obeying the
preferred node semantics. This is similar to the implementation for
general page allocation, as it uses a fallback mechanism to try multiple
preferred nodes first, and then all other nodes.
To avoid adding too many "#ifdef CONFIG_NUMA" check, add a helper function
in mempolicy.h to check whether a mempolicy is MPOL_PREFERRED_MANY.
[akpm: fix compling issue when merging with other hugetlb patch]
[Thanks to 0day bot for catching the !CONFIG_NUMA compiling issue]
[Michal Hocko: suggest to remove the #ifdef CONFIG_NUMA check]
Link: https://lore.kernel.org/r/20200630212517.308045-12-ben.widawsky@intel.com
Link: https://lkml.kernel.org/r/1627970362-61305-4-git-send-email-feng.tang@intel.com
Suggested-by: Michal Hocko <mhocko@...e.com>
Signed-off-by: Ben Widawsky <ben.widawsky@...el.com>
Co-developed-by: Feng Tang <feng.tang@...el.com>
Signed-off-by: Feng Tang <feng.tang@...el.com>
--
include/linux/mempolicy.h | 12 ++++++++++++
mm/hugetlb.c | 28 ++++++++++++++++++++++++----
2 files changed, 36 insertions(+), 4 deletions(-)
diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index 0117e1e..60d5e6c 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -187,6 +187,12 @@ extern void mpol_put_task_policy(struct task_struct *);
extern bool numa_demotion_enabled;
+static inline bool mpol_is_preferred_many(struct mempolicy *pol)
+{
+ return (pol->mode == MPOL_PREFERRED_MANY);
+}
+
+
#else
struct mempolicy {};
@@ -297,5 +303,11 @@ static inline nodemask_t *policy_nodemask_current(gfp_t gfp)
}
#define numa_demotion_enabled false
+
+static inline bool mpol_is_preferred_many(struct mempolicy *pol)
+{
+ return false;
+}
+
#endif /* CONFIG_NUMA */
#endif
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 95714fb..75ea8bc 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1145,7 +1145,7 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
unsigned long address, int avoid_reserve,
long chg)
{
- struct page *page;
+ struct page *page = NULL;
struct mempolicy *mpol;
gfp_t gfp_mask;
nodemask_t *nodemask;
@@ -1166,7 +1166,17 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
gfp_mask = htlb_alloc_mask(h);
nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
- page = dequeue_huge_page_nodemask(h, gfp_mask, nid, nodemask);
+
+ if (mpol_is_preferred_many(mpol)) {
+ page = dequeue_huge_page_nodemask(h, gfp_mask, nid, nodemask);
+
+ /* Fallback to all nodes if page==NULL */
+ nodemask = NULL;
+ }
+
+ if (!page)
+ page = dequeue_huge_page_nodemask(h, gfp_mask, nid, nodemask);
+
if (page && !avoid_reserve && vma_has_reserves(vma, chg)) {
SetHPageRestoreReserve(page);
h->resv_huge_pages--;
@@ -2147,9 +2157,19 @@ struct page *alloc_buddy_huge_page_with_mpol(struct hstate *h,
nodemask_t *nodemask;
nid = huge_node(vma, addr, gfp_mask, &mpol, &nodemask);
- page = alloc_surplus_huge_page(h, gfp_mask, nid, nodemask, false);
- mpol_cond_put(mpol);
+ if (mpol_is_preferred_many(mpol)) {
+ gfp_t gfp = gfp_mask | __GFP_NOWARN;
+ gfp &= ~(__GFP_DIRECT_RECLAIM | __GFP_NOFAIL);
+ page = alloc_surplus_huge_page(h, gfp, nid, nodemask, false);
+
+ /* Fallback to all nodes if page==NULL */
+ nodemask = NULL;
+ }
+
+ if (!page)
+ page = alloc_surplus_huge_page(h, gfp_mask, nid, nodemask, false);
+ mpol_cond_put(mpol);
return page;
}
--
2.7.4
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