From: Hou Tao <houtao1@huawei.com>
kernfs has already support ->mmap callback, however it doesn't support
->get_unmapped_area callback to return PMD-aligned or PUD-aligned
virtual address. The following patch will need it to support compound
page for p2pdma device memory, therefore add the necessary support for it.
When the ->get_unmapped_area callback is not defined in kernfs_ops or
the callback returns -EOPNOTSUPP, kernfs_get_unmapped_area() will
fallback to mm_get_unmapped_area().
Signed-off-by: Hou Tao <houtao1@huawei.com>
---
fs/kernfs/file.c | 37 +++++++++++++++++++++++++++++++++++++
include/linux/kernfs.h | 3 +++
2 files changed, 40 insertions(+)
diff --git a/fs/kernfs/file.c b/fs/kernfs/file.c
index 9adf36e6364b..9773b5734a2c 100644
--- a/fs/kernfs/file.c
+++ b/fs/kernfs/file.c
@@ -454,6 +454,39 @@ static const struct vm_operations_struct kernfs_vm_ops = {
.access = kernfs_vma_access,
};
+static unsigned long kernfs_get_unmapped_area(struct file *file, unsigned long uaddr,
+ unsigned long len, unsigned long pgoff,
+ unsigned long flags)
+{
+ struct kernfs_open_file *of = kernfs_of(file);
+ const struct kernfs_ops *ops;
+ long addr;
+
+ if (!(of->kn->flags & KERNFS_HAS_MMAP))
+ return -ENODEV;
+
+ mutex_lock(&of->mutex);
+
+ addr = -ENODEV;
+ if (!kernfs_get_active_of(of))
+ goto out_unlock;
+
+ ops = kernfs_ops(of->kn);
+ if (ops->get_unmapped_area) {
+ addr = ops->get_unmapped_area(of, uaddr, len, pgoff, flags);
+ if (!IS_ERR_VALUE(addr) || addr != -EOPNOTSUPP)
+ goto out_put;
+ }
+ addr = mm_get_unmapped_area(file, uaddr, len, pgoff, flags);
+
+out_put:
+ kernfs_put_active_of(of);
+out_unlock:
+ mutex_unlock(&of->mutex);
+
+ return addr;
+}
+
static int kernfs_fop_mmap(struct file *file, struct vm_area_struct *vma)
{
struct kernfs_open_file *of = kernfs_of(file);
@@ -1017,6 +1050,7 @@ const struct file_operations kernfs_file_fops = {
.write_iter = kernfs_fop_write_iter,
.llseek = kernfs_fop_llseek,
.mmap = kernfs_fop_mmap,
+ .get_unmapped_area = kernfs_get_unmapped_area,
.open = kernfs_fop_open,
.release = kernfs_fop_release,
.poll = kernfs_fop_poll,
@@ -1052,6 +1086,9 @@ struct kernfs_node *__kernfs_create_file(struct kernfs_node *parent,
unsigned flags;
int rc;
+ if (ops->get_unmapped_area && !ops->mmap)
+ return ERR_PTR(-EINVAL);
+
flags = KERNFS_FILE;
kn = kernfs_new_node(parent, name, (mode & S_IALLUGO) | S_IFREG,
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index b5a5f32fdfd1..9467b0a2b339 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -324,6 +324,9 @@ struct kernfs_ops {
int (*mmap)(struct kernfs_open_file *of, struct vm_area_struct *vma);
loff_t (*llseek)(struct kernfs_open_file *of, loff_t offset, int whence);
+ unsigned long (*get_unmapped_area)(struct kernfs_open_file *of, unsigned long uaddr,
+ unsigned long len, unsigned long pgoff,
+ unsigned long flags);
};
/*
--
2.29.2Hi Hou,
kernel test robot noticed the following build errors:
[auto build test ERROR on driver-core/driver-core-testing]
[also build test ERROR on driver-core/driver-core-next driver-core/driver-core-linus akpm-mm/mm-everything linus/master v6.19-rc1 next-20251219]
[cannot apply to pci/next pci/for-linus]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Hou-Tao/PCI-P2PDMA-Release-the-per-cpu-ref-of-pgmap-when-vm_insert_page-fails/20251220-121804
base: driver-core/driver-core-testing
patch link: https://lore.kernel.org/r/20251220040446.274991-4-houtao%40huaweicloud.com
patch subject: [PATCH 03/13] kernfs: add support for get_unmapped_area callback
config: sh-allnoconfig (https://download.01.org/0day-ci/archive/20251220/202512202307.ewUcqBQV-lkp@intel.com/config)
compiler: sh4-linux-gcc (GCC) 15.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251220/202512202307.ewUcqBQV-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202512202307.ewUcqBQV-lkp@intel.com/
All errors (new ones prefixed by >>):
fs/kernfs/file.c: In function 'kernfs_get_unmapped_area':
>> fs/kernfs/file.c:480:16: error: implicit declaration of function 'mm_get_unmapped_area'; did you mean 'get_unmapped_area'? [-Wimplicit-function-declaration]
480 | addr = mm_get_unmapped_area(file, uaddr, len, pgoff, flags);
| ^~~~~~~~~~~~~~~~~~~~
| get_unmapped_area
vim +480 fs/kernfs/file.c
456
457 static unsigned long kernfs_get_unmapped_area(struct file *file, unsigned long uaddr,
458 unsigned long len, unsigned long pgoff,
459 unsigned long flags)
460 {
461 struct kernfs_open_file *of = kernfs_of(file);
462 const struct kernfs_ops *ops;
463 long addr;
464
465 if (!(of->kn->flags & KERNFS_HAS_MMAP))
466 return -ENODEV;
467
468 mutex_lock(&of->mutex);
469
470 addr = -ENODEV;
471 if (!kernfs_get_active_of(of))
472 goto out_unlock;
473
474 ops = kernfs_ops(of->kn);
475 if (ops->get_unmapped_area) {
476 addr = ops->get_unmapped_area(of, uaddr, len, pgoff, flags);
477 if (!IS_ERR_VALUE(addr) || addr != -EOPNOTSUPP)
478 goto out_put;
479 }
> 480 addr = mm_get_unmapped_area(file, uaddr, len, pgoff, flags);
481
482 out_put:
483 kernfs_put_active_of(of);
484 out_unlock:
485 mutex_unlock(&of->mutex);
486
487 return addr;
488 }
489
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
Hi Hou,
kernel test robot noticed the following build errors:
[auto build test ERROR on driver-core/driver-core-testing]
[also build test ERROR on driver-core/driver-core-next driver-core/driver-core-linus akpm-mm/mm-everything linus/master v6.19-rc1 next-20251219]
[cannot apply to pci/next pci/for-linus]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]
url: https://github.com/intel-lab-lkp/linux/commits/Hou-Tao/PCI-P2PDMA-Release-the-per-cpu-ref-of-pgmap-when-vm_insert_page-fails/20251220-121804
base: driver-core/driver-core-testing
patch link: https://lore.kernel.org/r/20251220040446.274991-4-houtao%40huaweicloud.com
patch subject: [PATCH 03/13] kernfs: add support for get_unmapped_area callback
config: arm-allnoconfig (https://download.01.org/0day-ci/archive/20251220/202512202338.qFqw6FI8-lkp@intel.com/config)
compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project b324c9f4fa112d61a553bf489b5f4f7ceea05ea8)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251220/202512202338.qFqw6FI8-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202512202338.qFqw6FI8-lkp@intel.com/
All errors (new ones prefixed by >>):
>> fs/kernfs/file.c:480:9: error: call to undeclared function 'mm_get_unmapped_area'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
480 | addr = mm_get_unmapped_area(file, uaddr, len, pgoff, flags);
| ^
fs/kernfs/file.c:480:9: note: did you mean '__get_unmapped_area'?
include/linux/mm.h:3671:1: note: '__get_unmapped_area' declared here
3671 | __get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
| ^
1 error generated.
vim +/mm_get_unmapped_area +480 fs/kernfs/file.c
456
457 static unsigned long kernfs_get_unmapped_area(struct file *file, unsigned long uaddr,
458 unsigned long len, unsigned long pgoff,
459 unsigned long flags)
460 {
461 struct kernfs_open_file *of = kernfs_of(file);
462 const struct kernfs_ops *ops;
463 long addr;
464
465 if (!(of->kn->flags & KERNFS_HAS_MMAP))
466 return -ENODEV;
467
468 mutex_lock(&of->mutex);
469
470 addr = -ENODEV;
471 if (!kernfs_get_active_of(of))
472 goto out_unlock;
473
474 ops = kernfs_ops(of->kn);
475 if (ops->get_unmapped_area) {
476 addr = ops->get_unmapped_area(of, uaddr, len, pgoff, flags);
477 if (!IS_ERR_VALUE(addr) || addr != -EOPNOTSUPP)
478 goto out_put;
479 }
> 480 addr = mm_get_unmapped_area(file, uaddr, len, pgoff, flags);
481
482 out_put:
483 kernfs_put_active_of(of);
484 out_unlock:
485 mutex_unlock(&of->mutex);
486
487 return addr;
488 }
489
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
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