From: Joao Martins <joao.m.martins@oracle.com>
To: linux-nvdimm@lists.01.org
Cc: Dan Williams <dan.j.williams@intel.com>,
Vishal Verma <vishal.l.verma@intel.com>,
Dave Jiang <dave.jiang@intel.com>,
Ira Weiny <ira.weiny@intel.com>,
Alex Williamson <alex.williamson@redhat.com>,
Cornelia Huck <cohuck@redhat.com>,
kvm@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H . Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Liran Alon <liran.alon@oracle.com>,
Nikita Leshenko <nikita.leshchenko@oracle.com>,
Barret Rhoden <brho@google.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Matthew Wilcox <willy@infradead.org>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: [PATCH RFC 05/10] device-dax: Do not enforce MADV_DONTFORK on mmap()
Date: Fri, 10 Jan 2020 19:03:08 +0000 [thread overview]
Message-ID: <20200110190313.17144-6-joao.m.martins@oracle.com> (raw)
In-Reply-To: <20200110190313.17144-1-joao.m.martins@oracle.com>
Currently check_vma() checks for VM_DONTCOPY for a device-dax
when the dax region is not backed by devmap (i.e. PFN_MAP is not set).
VM_DONTCOPY is set through madvise(MADV_DONTFORK) and it only sets it
at an address returned from mmap(). check_vma() is called at devdax
mmap hence checking VM_DONTCOPY prevents a process from mmap-ing the
device.
Let's not enforce MADV_DONTFORK at mmap(), but rather when it actually
gets used (on fault). The assumptions don't change, as it is
expected to still retain/madvise MADV_DONTFORK after mmap.
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
---
drivers/dax/device.c | 28 ++++++++++++++++++++--------
1 file changed, 20 insertions(+), 8 deletions(-)
diff --git a/drivers/dax/device.c b/drivers/dax/device.c
index 1af823b2fe6b..c6a7f5e12c54 100644
--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c
@@ -14,7 +14,7 @@
#include "dax-private.h"
#include "bus.h"
-static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
+static int check_vma_mmap(struct dev_dax *dev_dax, struct vm_area_struct *vma,
const char *func)
{
struct dax_region *dax_region = dev_dax->region;
@@ -41,17 +41,29 @@ static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
return -EINVAL;
}
- if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) == PFN_DEV
- && (vma->vm_flags & VM_DONTCOPY) == 0) {
+ if (!vma_is_dax(vma)) {
dev_info_ratelimited(dev,
- "%s: %s: fail, dax range requires MADV_DONTFORK\n",
+ "%s: %s: fail, vma is not DAX capable\n",
current->comm, func);
return -EINVAL;
}
- if (!vma_is_dax(vma)) {
- dev_info_ratelimited(dev,
- "%s: %s: fail, vma is not DAX capable\n",
+ return 0;
+}
+
+static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
+ const char *func)
+{
+ int rc;
+
+ rc = check_vma_mmap(dev_dax, vma, func);
+ if (rc < 0)
+ return rc;
+
+ if ((dev_dax->region->pfn_flags & (PFN_DEV|PFN_MAP)) == PFN_DEV
+ && (vma->vm_flags & VM_DONTCOPY) == 0) {
+ dev_info_ratelimited(&dev_dax->dev,
+ "%s: %s: fail, dax range requires MADV_DONTFORK\n",
current->comm, func);
return -EINVAL;
}
@@ -315,7 +327,7 @@ static int dax_mmap(struct file *filp, struct vm_area_struct *vma)
* fault time.
*/
id = dax_read_lock();
- rc = check_vma(dev_dax, vma, __func__);
+ rc = check_vma_mmap(dev_dax, vma, __func__);
dax_read_unlock(id);
if (rc)
return rc;
--
2.17.1
next prev parent reply other threads:[~2020-01-10 19:06 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-10 19:03 [PATCH RFC 00/10] device-dax: Support devices without PFN metadata Joao Martins
2020-01-10 19:03 ` [PATCH RFC 01/10] mm: Add pmd support for _PAGE_SPECIAL Joao Martins
2020-02-03 21:34 ` Matthew Wilcox
2020-02-04 16:14 ` Joao Martins
2020-01-10 19:03 ` [PATCH RFC 02/10] mm: Handle pmd entries in follow_pfn() Joao Martins
2020-02-03 21:37 ` Matthew Wilcox
2020-02-04 16:17 ` Joao Martins
2020-01-10 19:03 ` [PATCH RFC 03/10] mm: Add pud support for _PAGE_SPECIAL Joao Martins
2020-01-10 19:03 ` [PATCH RFC 04/10] mm: Handle pud entries in follow_pfn() Joao Martins
2020-01-10 19:03 ` Joao Martins [this message]
2020-01-10 19:03 ` [PATCH RFC 06/10] device-dax: Introduce pfn_flags helper Joao Martins
2020-01-10 19:03 ` [PATCH RFC 07/10] device-dax: Add support for PFN_SPECIAL flags Joao Martins
2020-01-10 19:03 ` [PATCH RFC 08/10] dax/pmem: Add device-dax support for PFN_MODE_NONE Joao Martins
2020-01-10 19:03 ` [PATCH RFC 09/10] vfio/type1: Use follow_pfn for VM_FPNMAP VMAs Joao Martins
2020-02-07 21:08 ` Jason Gunthorpe
2020-02-11 16:23 ` Joao Martins
2020-02-11 16:50 ` Jason Gunthorpe
2020-01-10 19:03 ` [PATCH RFC 10/10] nvdimm/e820: add multiple namespaces support Joao Martins
2020-02-04 15:28 ` Barret Rhoden
2020-02-04 16:44 ` Dan Williams
2020-02-04 18:20 ` Barret Rhoden
2020-02-04 19:24 ` Joao Martins
2020-02-04 21:43 ` Dan Williams
2020-02-04 21:57 ` Barret Rhoden
2020-02-04 1:24 ` [PATCH RFC 00/10] device-dax: Support devices without PFN metadata Dan Williams
2020-02-04 19:07 ` Joao Martins
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