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Date:   Fri, 21 Oct 2022 16:36:22 +0000
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Message-ID: <20221021163703.3218176-7-jthoughton@google.com>
Subject: [RFC PATCH v2 06/47] hugetlb: extend vma lock for shared vmas
From:   James Houghton <jthoughton@google.com>
To:     Mike Kravetz <mike.kravetz@oracle.com>,
        Muchun Song <songmuchun@bytedance.com>,
        Peter Xu <peterx@redhat.com>
Cc:     David Hildenbrand <david@redhat.com>,
        David Rientjes <rientjes@google.com>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Mina Almasry <almasrymina@google.com>,
        "Zach O'Keefe" <zokeefe@google.com>,
        Manish Mishra <manish.mishra@nutanix.com>,
        Naoya Horiguchi <naoya.horiguchi@nec.com>,
        "Dr . David Alan Gilbert" <dgilbert@redhat.com>,
        "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Baolin Wang <baolin.wang@linux.alibaba.com>,
        Miaohe Lin <linmiaohe@huawei.com>,
        Yang Shi <shy828301@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        James Houghton <jthoughton@google.com>
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Precedence: bulk

This allows us to add more data into the shared structure, which we will
use to store whether or not HGM is enabled for this VMA or not, as HGM
is only available for shared mappings.

It may be better to include HGM as a VMA flag instead of extending the
VMA lock structure.

Signed-off-by: James Houghton <jthoughton@google.com>
---
 include/linux/hugetlb.h |  4 +++
 mm/hugetlb.c            | 65 +++++++++++++++++++++--------------------
 2 files changed, 37 insertions(+), 32 deletions(-)

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index a899bc76d677..534958499ac4 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -121,6 +121,10 @@ struct hugetlb_vma_lock {
 	struct vm_area_struct *vma;
 };
 
+struct hugetlb_shared_vma_data {
+	struct hugetlb_vma_lock vma_lock;
+};
+
 extern struct resv_map *resv_map_alloc(void);
 void resv_map_release(struct kref *ref);
 
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index dc82256b89dd..5ae8bc8c928e 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -91,8 +91,8 @@ struct mutex *hugetlb_fault_mutex_table ____cacheline_aligned_in_smp;
 
 /* Forward declaration */
 static int hugetlb_acct_memory(struct hstate *h, long delta);
-static void hugetlb_vma_lock_free(struct vm_area_struct *vma);
-static int hugetlb_vma_lock_alloc(struct vm_area_struct *vma);
+static void hugetlb_vma_data_free(struct vm_area_struct *vma);
+static int hugetlb_vma_data_alloc(struct vm_area_struct *vma);
 static void __hugetlb_vma_unlock_write_free(struct vm_area_struct *vma);
 
 static inline bool subpool_is_free(struct hugepage_subpool *spool)
@@ -4643,11 +4643,11 @@ static void hugetlb_vm_op_open(struct vm_area_struct *vma)
 		if (vma_lock) {
 			if (vma_lock->vma != vma) {
 				vma->vm_private_data = NULL;
-				hugetlb_vma_lock_alloc(vma);
+				hugetlb_vma_data_alloc(vma);
 			} else
 				pr_warn("HugeTLB: vma_lock already exists in %s.\n", __func__);
 		} else
-			hugetlb_vma_lock_alloc(vma);
+			hugetlb_vma_data_alloc(vma);
 	}
 }
 
@@ -4659,7 +4659,7 @@ static void hugetlb_vm_op_close(struct vm_area_struct *vma)
 	unsigned long reserve, start, end;
 	long gbl_reserve;
 
-	hugetlb_vma_lock_free(vma);
+	hugetlb_vma_data_free(vma);
 
 	resv = vma_resv_map(vma);
 	if (!resv || !is_vma_resv_set(vma, HPAGE_RESV_OWNER))
@@ -6629,7 +6629,7 @@ bool hugetlb_reserve_pages(struct inode *inode,
 	/*
 	 * vma specific semaphore used for pmd sharing synchronization
 	 */
-	hugetlb_vma_lock_alloc(vma);
+	hugetlb_vma_data_alloc(vma);
 
 	/*
 	 * Only apply hugepage reservation if asked. At fault time, an
@@ -6753,7 +6753,7 @@ bool hugetlb_reserve_pages(struct inode *inode,
 	hugetlb_cgroup_uncharge_cgroup_rsvd(hstate_index(h),
 					    chg * pages_per_huge_page(h), h_cg);
 out_err:
-	hugetlb_vma_lock_free(vma);
+	hugetlb_vma_data_free(vma);
 	if (!vma || vma->vm_flags & VM_MAYSHARE)
 		/* Only call region_abort if the region_chg succeeded but the
 		 * region_add failed or didn't run.
@@ -6901,55 +6901,55 @@ static bool __vma_shareable_flags_pmd(struct vm_area_struct *vma)
 void hugetlb_vma_lock_read(struct vm_area_struct *vma)
 {
 	if (__vma_shareable_flags_pmd(vma)) {
-		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
+		struct hugetlb_shared_vma_data *data = vma->vm_private_data;
 
-		down_read(&vma_lock->rw_sema);
+		down_read(&data->vma_lock.rw_sema);
 	}
 }
 
 void hugetlb_vma_unlock_read(struct vm_area_struct *vma)
 {
 	if (__vma_shareable_flags_pmd(vma)) {
-		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
+		struct hugetlb_shared_vma_data *data = vma->vm_private_data;
 
-		up_read(&vma_lock->rw_sema);
+		up_read(&data->vma_lock.rw_sema);
 	}
 }
 
 void hugetlb_vma_lock_write(struct vm_area_struct *vma)
 {
 	if (__vma_shareable_flags_pmd(vma)) {
-		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
+		struct hugetlb_shared_vma_data *data = vma->vm_private_data;
 
-		down_write(&vma_lock->rw_sema);
+		down_write(&data->vma_lock.rw_sema);
 	}
 }
 
 void hugetlb_vma_unlock_write(struct vm_area_struct *vma)
 {
 	if (__vma_shareable_flags_pmd(vma)) {
-		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
+		struct hugetlb_shared_vma_data *data = vma->vm_private_data;
 
-		up_write(&vma_lock->rw_sema);
+		up_write(&data->vma_lock.rw_sema);
 	}
 }
 
 int hugetlb_vma_trylock_write(struct vm_area_struct *vma)
 {
-	struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
+	struct hugetlb_shared_vma_data *data = vma->vm_private_data;
 
 	if (!__vma_shareable_flags_pmd(vma))
 		return 1;
 
-	return down_write_trylock(&vma_lock->rw_sema);
+	return down_write_trylock(&data->vma_lock.rw_sema);
 }
 
 void hugetlb_vma_assert_locked(struct vm_area_struct *vma)
 {
 	if (__vma_shareable_flags_pmd(vma)) {
-		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
+		struct hugetlb_shared_vma_data *data = vma->vm_private_data;
 
-		lockdep_assert_held(&vma_lock->rw_sema);
+		lockdep_assert_held(&data->vma_lock.rw_sema);
 	}
 }
 
@@ -6985,7 +6985,7 @@ static void __hugetlb_vma_unlock_write_free(struct vm_area_struct *vma)
 	}
 }
 
-static void hugetlb_vma_lock_free(struct vm_area_struct *vma)
+static void hugetlb_vma_data_free(struct vm_area_struct *vma)
 {
 	/*
 	 * Only present in sharable vmas.
@@ -6994,16 +6994,17 @@ static void hugetlb_vma_lock_free(struct vm_area_struct *vma)
 		return;
 
 	if (vma->vm_private_data) {
-		struct hugetlb_vma_lock *vma_lock = vma->vm_private_data;
+		struct hugetlb_shared_vma_data *data = vma->vm_private_data;
+		struct hugetlb_vma_lock *vma_lock = &data->vma_lock;
 
 		down_write(&vma_lock->rw_sema);
 		__hugetlb_vma_unlock_write_put(vma_lock);
 	}
 }
 
-static int hugetlb_vma_lock_alloc(struct vm_area_struct *vma)
+static int hugetlb_vma_data_alloc(struct vm_area_struct *vma)
 {
-	struct hugetlb_vma_lock *vma_lock;
+	struct hugetlb_shared_vma_data *data;
 
 	/* Only establish in (flags) sharable vmas */
 	if (!vma || !(vma->vm_flags & VM_MAYSHARE))
@@ -7013,8 +7014,8 @@ static int hugetlb_vma_lock_alloc(struct vm_area_struct *vma)
 	if (vma->vm_private_data)
 		return 0;
 
-	vma_lock = kmalloc(sizeof(*vma_lock), GFP_KERNEL);
-	if (!vma_lock) {
+	data = kmalloc(sizeof(*data), GFP_KERNEL);
+	if (!data) {
 		/*
 		 * If we can not allocate structure, then vma can not
 		 * participate in pmd sharing.  This is only a possible
@@ -7025,14 +7026,14 @@ static int hugetlb_vma_lock_alloc(struct vm_area_struct *vma)
 		 * until the file is removed.  Warn in the unlikely case of
 		 * allocation failure.
 		 */
-		pr_warn_once("HugeTLB: unable to allocate vma specific lock\n");
+		pr_warn_once("HugeTLB: unable to allocate vma shared data\n");
 		return -ENOMEM;
 	}
 
-	kref_init(&vma_lock->refs);
-	init_rwsem(&vma_lock->rw_sema);
-	vma_lock->vma = vma;
-	vma->vm_private_data = vma_lock;
+	kref_init(&data->vma_lock.refs);
+	init_rwsem(&data->vma_lock.rw_sema);
+	data->vma_lock.vma = vma;
+	vma->vm_private_data = data;
 	return 0;
 }
 
@@ -7157,11 +7158,11 @@ static void __hugetlb_vma_unlock_write_free(struct vm_area_struct *vma)
 {
 }
 
-static void hugetlb_vma_lock_free(struct vm_area_struct *vma)
+static void hugetlb_vma_data_free(struct vm_area_struct *vma)
 {
 }
 
-static int hugetlb_vma_lock_alloc(struct vm_area_struct *vma)
+static int hugetlb_vma_data_alloc(struct vm_area_struct *vma)
 {
 	return 0;
 }
-- 
2.38.0.135.g90850a2211-goog