+ mm-add-account_locked_vm-utility-function.patch added to -mm tree

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The patch titled
     Subject: mm: add account_locked_vm utility function
has been added to the -mm tree.  Its filename is
     mm-add-account_locked_vm-utility-function.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/mm-add-account_locked_vm-utility-function.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/mm-add-account_locked_vm-utility-function.patch

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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
Subject: mm: add account_locked_vm utility function

locked_vm accounting is done roughly the same way in five places, so unify
them in a helper.  Standardize the debug prints, which vary slightly, but
include the helper's caller to disambiguate between callsites.

Error codes stay the same, so user-visible behavior does too.  The one
exception is that the -EPERM case in tce_account_locked_vm is removed
because Alexey has never seen it triggered.

Link: http://lkml.kernel.org/r/20190524175045.26897-1-daniel.m.jordan@xxxxxxxxxx
Signed-off-by: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
Tested-by: Alexey Kardashevskiy <aik@xxxxxxxxx>
Cc: Alan Tull <atull@xxxxxxxxxx>
Cc: Alex Williamson <alex.williamson@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Moritz Fischer <mdf@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxxx>
Cc: Steve Sistare <steven.sistare@xxxxxxxxxx>
Cc: Wu Hao <hao.wu@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 arch/powerpc/kvm/book3s_64_vio.c     |   44 +-------------------
 arch/powerpc/mm/book3s64/iommu_api.c |   41 +-----------------
 drivers/fpga/dfl-afu-dma-region.c    |   53 +-----------------------
 drivers/vfio/vfio_iommu_spapr_tce.c  |   54 ++-----------------------
 drivers/vfio/vfio_iommu_type1.c      |   17 -------
 include/linux/mm.h                   |   19 ++++++++
 mm/util.c                            |   46 +++++++++++++++++++++
 7 files changed, 84 insertions(+), 190 deletions(-)

--- a/arch/powerpc/kvm/book3s_64_vio.c~mm-add-account_locked_vm-utility-function
+++ a/arch/powerpc/kvm/book3s_64_vio.c
@@ -30,6 +30,7 @@
 #include <linux/anon_inodes.h>
 #include <linux/iommu.h>
 #include <linux/file.h>
+#include <linux/mm.h>
 
 #include <asm/kvm_ppc.h>
 #include <asm/kvm_book3s.h>
@@ -56,43 +57,6 @@ static unsigned long kvmppc_stt_pages(un
 	return tce_pages + ALIGN(stt_bytes, PAGE_SIZE) / PAGE_SIZE;
 }
 
-static long kvmppc_account_memlimit(unsigned long stt_pages, bool inc)
-{
-	long ret = 0;
-
-	if (!current || !current->mm)
-		return ret; /* process exited */
-
-	down_write(&current->mm->mmap_sem);
-
-	if (inc) {
-		unsigned long locked, lock_limit;
-
-		locked = current->mm->locked_vm + stt_pages;
-		lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
-		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
-			ret = -ENOMEM;
-		else
-			current->mm->locked_vm += stt_pages;
-	} else {
-		if (WARN_ON_ONCE(stt_pages > current->mm->locked_vm))
-			stt_pages = current->mm->locked_vm;
-
-		current->mm->locked_vm -= stt_pages;
-	}
-
-	pr_debug("[%d] RLIMIT_MEMLOCK KVM %c%ld %ld/%ld%s\n", current->pid,
-			inc ? '+' : '-',
-			stt_pages << PAGE_SHIFT,
-			current->mm->locked_vm << PAGE_SHIFT,
-			rlimit(RLIMIT_MEMLOCK),
-			ret ? " - exceeded" : "");
-
-	up_write(&current->mm->mmap_sem);
-
-	return ret;
-}
-
 static void kvm_spapr_tce_iommu_table_free(struct rcu_head *head)
 {
 	struct kvmppc_spapr_tce_iommu_table *stit = container_of(head,
@@ -302,7 +266,7 @@ static int kvm_spapr_tce_release(struct
 
 	kvm_put_kvm(stt->kvm);
 
-	kvmppc_account_memlimit(
+	account_locked_vm(current->mm,
 		kvmppc_stt_pages(kvmppc_tce_pages(stt->size)), false);
 	call_rcu(&stt->rcu, release_spapr_tce_table);
 
@@ -327,7 +291,7 @@ long kvm_vm_ioctl_create_spapr_tce(struc
 		return -EINVAL;
 
 	npages = kvmppc_tce_pages(size);
-	ret = kvmppc_account_memlimit(kvmppc_stt_pages(npages), true);
+	ret = account_locked_vm(current->mm, kvmppc_stt_pages(npages), true);
 	if (ret)
 		return ret;
 
@@ -373,7 +337,7 @@ long kvm_vm_ioctl_create_spapr_tce(struc
 
 	kfree(stt);
  fail_acct:
-	kvmppc_account_memlimit(kvmppc_stt_pages(npages), false);
+	account_locked_vm(current->mm, kvmppc_stt_pages(npages), false);
 	return ret;
 }
 
--- a/arch/powerpc/mm/book3s64/iommu_api.c~mm-add-account_locked_vm-utility-function
+++ a/arch/powerpc/mm/book3s64/iommu_api.c
@@ -19,6 +19,7 @@
 #include <linux/hugetlb.h>
 #include <linux/swap.h>
 #include <linux/sizes.h>
+#include <linux/mm.h>
 #include <asm/mmu_context.h>
 #include <asm/pte-walk.h>
 #include <linux/mm_inline.h>
@@ -51,40 +52,6 @@ struct mm_iommu_table_group_mem_t {
 	u64 dev_hpa;		/* Device memory base address */
 };
 
-static long mm_iommu_adjust_locked_vm(struct mm_struct *mm,
-		unsigned long npages, bool incr)
-{
-	long ret = 0, locked, lock_limit;
-
-	if (!npages)
-		return 0;
-
-	down_write(&mm->mmap_sem);
-
-	if (incr) {
-		locked = mm->locked_vm + npages;
-		lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
-		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
-			ret = -ENOMEM;
-		else
-			mm->locked_vm += npages;
-	} else {
-		if (WARN_ON_ONCE(npages > mm->locked_vm))
-			npages = mm->locked_vm;
-		mm->locked_vm -= npages;
-	}
-
-	pr_debug("[%d] RLIMIT_MEMLOCK HASH64 %c%ld %ld/%ld\n",
-			current ? current->pid : 0,
-			incr ? '+' : '-',
-			npages << PAGE_SHIFT,
-			mm->locked_vm << PAGE_SHIFT,
-			rlimit(RLIMIT_MEMLOCK));
-	up_write(&mm->mmap_sem);
-
-	return ret;
-}
-
 bool mm_iommu_preregistered(struct mm_struct *mm)
 {
 	return !list_empty(&mm->context.iommu_group_mem_list);
@@ -101,7 +68,7 @@ static long mm_iommu_do_alloc(struct mm_
 	unsigned long entry, chunk;
 
 	if (dev_hpa == MM_IOMMU_TABLE_INVALID_HPA) {
-		ret = mm_iommu_adjust_locked_vm(mm, entries, true);
+		ret = account_locked_vm(mm, entries, true);
 		if (ret)
 			return ret;
 
@@ -216,7 +183,7 @@ free_exit:
 	kfree(mem);
 
 unlock_exit:
-	mm_iommu_adjust_locked_vm(mm, locked_entries, false);
+	account_locked_vm(mm, locked_entries, false);
 
 	return ret;
 }
@@ -316,7 +283,7 @@ long mm_iommu_put(struct mm_struct *mm,
 unlock_exit:
 	mutex_unlock(&mem_list_mutex);
 
-	mm_iommu_adjust_locked_vm(mm, unlock_entries, false);
+	account_locked_vm(mm, unlock_entries, false);
 
 	return ret;
 }
--- a/drivers/fpga/dfl-afu-dma-region.c~mm-add-account_locked_vm-utility-function
+++ a/drivers/fpga/dfl-afu-dma-region.c
@@ -12,6 +12,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/sched/signal.h>
 #include <linux/uaccess.h>
+#include <linux/mm.h>
 
 #include "dfl-afu.h"
 
@@ -32,52 +33,6 @@ void afu_dma_region_init(struct dfl_feat
 }
 
 /**
- * afu_dma_adjust_locked_vm - adjust locked memory
- * @dev: port device
- * @npages: number of pages
- * @incr: increase or decrease locked memory
- *
- * Increase or decrease the locked memory size with npages input.
- *
- * Return 0 on success.
- * Return -ENOMEM if locked memory size is over the limit and no CAP_IPC_LOCK.
- */
-static int afu_dma_adjust_locked_vm(struct device *dev, long npages, bool incr)
-{
-	unsigned long locked, lock_limit;
-	int ret = 0;
-
-	/* the task is exiting. */
-	if (!current->mm)
-		return 0;
-
-	down_write(&current->mm->mmap_sem);
-
-	if (incr) {
-		locked = current->mm->locked_vm + npages;
-		lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
-
-		if (locked > lock_limit && !capable(CAP_IPC_LOCK))
-			ret = -ENOMEM;
-		else
-			current->mm->locked_vm += npages;
-	} else {
-		if (WARN_ON_ONCE(npages > current->mm->locked_vm))
-			npages = current->mm->locked_vm;
-		current->mm->locked_vm -= npages;
-	}
-
-	dev_dbg(dev, "[%d] RLIMIT_MEMLOCK %c%ld %ld/%ld%s\n", current->pid,
-		incr ? '+' : '-', npages << PAGE_SHIFT,
-		current->mm->locked_vm << PAGE_SHIFT, rlimit(RLIMIT_MEMLOCK),
-		ret ? "- exceeded" : "");
-
-	up_write(&current->mm->mmap_sem);
-
-	return ret;
-}
-
-/**
  * afu_dma_pin_pages - pin pages of given dma memory region
  * @pdata: feature device platform data
  * @region: dma memory region to be pinned
@@ -92,7 +47,7 @@ static int afu_dma_pin_pages(struct dfl_
 	struct device *dev = &pdata->dev->dev;
 	int ret, pinned;
 
-	ret = afu_dma_adjust_locked_vm(dev, npages, true);
+	ret = account_locked_vm(current->mm, npages, true);
 	if (ret)
 		return ret;
 
@@ -121,7 +76,7 @@ put_pages:
 free_pages:
 	kfree(region->pages);
 unlock_vm:
-	afu_dma_adjust_locked_vm(dev, npages, false);
+	account_locked_vm(current->mm, npages, false);
 	return ret;
 }
 
@@ -141,7 +96,7 @@ static void afu_dma_unpin_pages(struct d
 
 	put_all_pages(region->pages, npages);
 	kfree(region->pages);
-	afu_dma_adjust_locked_vm(dev, npages, false);
+	account_locked_vm(current->mm, npages, false);
 
 	dev_dbg(dev, "%ld pages unpinned\n", npages);
 }
--- a/drivers/vfio/vfio_iommu_spapr_tce.c~mm-add-account_locked_vm-utility-function
+++ a/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -22,6 +22,7 @@
 #include <linux/vmalloc.h>
 #include <linux/sched/mm.h>
 #include <linux/sched/signal.h>
+#include <linux/mm.h>
 
 #include <asm/iommu.h>
 #include <asm/tce.h>
@@ -34,51 +35,6 @@
 static void tce_iommu_detach_group(void *iommu_data,
 		struct iommu_group *iommu_group);
 
-static long try_increment_locked_vm(struct mm_struct *mm, long npages)
-{
-	long ret = 0, locked, lock_limit;
-
-	if (WARN_ON_ONCE(!mm))
-		return -EPERM;
-
-	if (!npages)
-		return 0;
-
-	down_write(&mm->mmap_sem);
-	locked = mm->locked_vm + npages;
-	lock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
-	if (locked > lock_limit && !capable(CAP_IPC_LOCK))
-		ret = -ENOMEM;
-	else
-		mm->locked_vm += npages;
-
-	pr_debug("[%d] RLIMIT_MEMLOCK +%ld %ld/%ld%s\n", current->pid,
-			npages << PAGE_SHIFT,
-			mm->locked_vm << PAGE_SHIFT,
-			rlimit(RLIMIT_MEMLOCK),
-			ret ? " - exceeded" : "");
-
-	up_write(&mm->mmap_sem);
-
-	return ret;
-}
-
-static void decrement_locked_vm(struct mm_struct *mm, long npages)
-{
-	if (!mm || !npages)
-		return;
-
-	down_write(&mm->mmap_sem);
-	if (WARN_ON_ONCE(npages > mm->locked_vm))
-		npages = mm->locked_vm;
-	mm->locked_vm -= npages;
-	pr_debug("[%d] RLIMIT_MEMLOCK -%ld %ld/%ld\n", current->pid,
-			npages << PAGE_SHIFT,
-			mm->locked_vm << PAGE_SHIFT,
-			rlimit(RLIMIT_MEMLOCK));
-	up_write(&mm->mmap_sem);
-}
-
 /*
  * VFIO IOMMU fd for SPAPR_TCE IOMMU implementation
  *
@@ -336,7 +292,7 @@ static int tce_iommu_enable(struct tce_c
 		return ret;
 
 	locked = table_group->tce32_size >> PAGE_SHIFT;
-	ret = try_increment_locked_vm(container->mm, locked);
+	ret = account_locked_vm(container->mm, locked, true);
 	if (ret)
 		return ret;
 
@@ -355,7 +311,7 @@ static void tce_iommu_disable(struct tce
 	container->enabled = false;
 
 	BUG_ON(!container->mm);
-	decrement_locked_vm(container->mm, container->locked_pages);
+	account_locked_vm(container->mm, container->locked_pages, false);
 }
 
 static void *tce_iommu_open(unsigned long arg)
@@ -659,7 +615,7 @@ static long tce_iommu_create_table(struc
 	if (!table_size)
 		return -EINVAL;
 
-	ret = try_increment_locked_vm(container->mm, table_size >> PAGE_SHIFT);
+	ret = account_locked_vm(container->mm, table_size >> PAGE_SHIFT, true);
 	if (ret)
 		return ret;
 
@@ -678,7 +634,7 @@ static void tce_iommu_free_table(struct
 	unsigned long pages = tbl->it_allocated_size >> PAGE_SHIFT;
 
 	iommu_tce_table_put(tbl);
-	decrement_locked_vm(container->mm, pages);
+	account_locked_vm(container->mm, pages, false);
 }
 
 static long tce_iommu_create_window(struct tce_container *container,
--- a/drivers/vfio/vfio_iommu_type1.c~mm-add-account_locked_vm-utility-function
+++ a/drivers/vfio/vfio_iommu_type1.c
@@ -275,21 +275,8 @@ static int vfio_lock_acct(struct vfio_dm
 
 	ret = down_write_killable(&mm->mmap_sem);
 	if (!ret) {
-		if (npage > 0) {
-			if (!dma->lock_cap) {
-				unsigned long limit;
-
-				limit = task_rlimit(dma->task,
-						RLIMIT_MEMLOCK) >> PAGE_SHIFT;
-
-				if (mm->locked_vm + npage > limit)
-					ret = -ENOMEM;
-			}
-		}
-
-		if (!ret)
-			mm->locked_vm += npage;
-
+		ret = __account_locked_vm(mm, abs(npage), npage > 0, dma->task,
+					  dma->lock_cap);
 		up_write(&mm->mmap_sem);
 	}
 
--- a/include/linux/mm.h~mm-add-account_locked_vm-utility-function
+++ a/include/linux/mm.h
@@ -1547,6 +1547,25 @@ long get_user_pages_unlocked(unsigned lo
 int get_user_pages_fast(unsigned long start, int nr_pages,
 			unsigned int gup_flags, struct page **pages);
 
+int __account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc,
+			struct task_struct *task, bool bypass_rlim);
+
+static inline int account_locked_vm(struct mm_struct *mm, unsigned long pages,
+				    bool inc)
+{
+	int ret;
+
+	if (pages == 0 || !mm)
+		return 0;
+
+	down_write(&mm->mmap_sem);
+	ret = __account_locked_vm(mm, pages, inc, current,
+				  capable(CAP_IPC_LOCK));
+	up_write(&mm->mmap_sem);
+
+	return ret;
+}
+
 /* Container for pinned pfns / pages */
 struct frame_vector {
 	unsigned int nr_allocated;	/* Number of frames we have space for */
--- a/mm/util.c~mm-add-account_locked_vm-utility-function
+++ a/mm/util.c
@@ -7,6 +7,7 @@
 #include <linux/err.h>
 #include <linux/sched.h>
 #include <linux/sched/mm.h>
+#include <linux/sched/signal.h>
 #include <linux/sched/task_stack.h>
 #include <linux/security.h>
 #include <linux/swap.h>
@@ -347,6 +348,51 @@ int __weak get_user_pages_fast(unsigned
 }
 EXPORT_SYMBOL_GPL(get_user_pages_fast);
 
+/**
+ * __account_locked_vm - account locked pages to an mm's locked_vm
+ * @mm:          mm to account against, may be NULL
+ * @pages:       number of pages to account
+ * @inc:         %true if @pages should be considered positive, %false if not
+ * @task:        task used to check RLIMIT_MEMLOCK
+ * @bypass_rlim: %true if checking RLIMIT_MEMLOCK should be skipped
+ *
+ * Assumes @task and @mm are valid (i.e. at least one reference on each), and
+ * that mmap_sem is held as writer.
+ *
+ * Return:
+ * * 0       on success
+ * * 0       if @mm is NULL (can happen for example if the task is exiting)
+ * * -ENOMEM if RLIMIT_MEMLOCK would be exceeded.
+ */
+int __account_locked_vm(struct mm_struct *mm, unsigned long pages, bool inc,
+			struct task_struct *task, bool bypass_rlim)
+{
+	unsigned long locked_vm, limit;
+	int ret = 0;
+
+	locked_vm = mm->locked_vm;
+	if (inc) {
+		if (!bypass_rlim) {
+			limit = task_rlimit(task, RLIMIT_MEMLOCK) >> PAGE_SHIFT;
+			if (locked_vm + pages > limit)
+				ret = -ENOMEM;
+		}
+		if (!ret)
+			mm->locked_vm = locked_vm + pages;
+	} else {
+		WARN_ON_ONCE(pages > locked_vm);
+		mm->locked_vm = locked_vm - pages;
+	}
+
+	pr_debug("%s: [%d] caller %ps %c%lu %lu/%lu%s\n", __func__, task->pid,
+		 (void *)_RET_IP_, (inc) ? '+' : '-', pages << PAGE_SHIFT,
+		 locked_vm << PAGE_SHIFT, task_rlimit(task, RLIMIT_MEMLOCK),
+		 ret ? " - exceeded" : "");
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__account_locked_vm);
+
 unsigned long vm_mmap_pgoff(struct file *file, unsigned long addr,
 	unsigned long len, unsigned long prot,
 	unsigned long flag, unsigned long pgoff)
_

Patches currently in -mm which might be from daniel.m.jordan@xxxxxxxxxx are

mm-add-account_locked_vm-utility-function.patch




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