From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Dan Williams <dan.j.williams@intel.com>,
Christoph Hellwig <hch@lst.de>,
Doug Ledford <dledford@redhat.com>,
Hal Rosenstock <hal.rosenstock@gmail.com>,
Inki Dae <inki.dae@samsung.com>, Jan Kara <jack@suse.cz>,
Jason Gunthorpe <jgg@mellanox.com>,
Jeff Moyer <jmoyer@redhat.com>,
Joonyoung Shim <jy0922.shim@samsung.com>,
Kyungmin Park <kyungmin.park@samsung.com>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Mel Gorman <mgorman@suse.de>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
Sean Hefty <sean.hefty@intel.com>,
Seung-Woo Kim <sw0312.kim@samsung.com>,
Vlastimil Babka <vbabka@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: [PATCH 4.9 33/39] mm: introduce get_user_pages_longterm
Date: Mon, 26 Feb 2018 21:20:54 +0100 [thread overview]
Message-ID: <20180226201645.125678735@linuxfoundation.org> (raw)
In-Reply-To: <20180226201643.660109883@linuxfoundation.org>
4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Dan Williams <dan.j.williams@intel.com>
commit 2bb6d2837083de722bfdc369cb0d76ce188dd9b4 upstream.
Patch series "introduce get_user_pages_longterm()", v2.
Here is a new get_user_pages api for cases where a driver intends to
keep an elevated page count indefinitely. This is distinct from usages
like iov_iter_get_pages where the elevated page counts are transient.
The iov_iter_get_pages cases immediately turn around and submit the
pages to a device driver which will put_page when the i/o operation
completes (under kernel control).
In the longterm case userspace is responsible for dropping the page
reference at some undefined point in the future. This is untenable for
filesystem-dax case where the filesystem is in control of the lifetime
of the block / page and needs reasonable limits on how long it can wait
for pages in a mapping to become idle.
Fixing filesystems to actually wait for dax pages to be idle before
blocks from a truncate/hole-punch operation are repurposed is saved for
a later patch series.
Also, allowing longterm registration of dax mappings is a future patch
series that introduces a "map with lease" semantic where the kernel can
revoke a lease and force userspace to drop its page references.
I have also tagged these for -stable to purposely break cases that might
assume that longterm memory registrations for filesystem-dax mappings
were supported by the kernel. The behavior regression this policy
change implies is one of the reasons we maintain the "dax enabled.
Warning: EXPERIMENTAL, use at your own risk" notification when mounting
a filesystem in dax mode.
It is worth noting the device-dax interface does not suffer the same
constraints since it does not support file space management operations
like hole-punch.
This patch (of 4):
Until there is a solution to the dma-to-dax vs truncate problem it is
not safe to allow long standing memory registrations against
filesytem-dax vmas. Device-dax vmas do not have this problem and are
explicitly allowed.
This is temporary until a "memory registration with layout-lease"
mechanism can be implemented for the affected sub-systems (RDMA and
V4L2).
[akpm@linux-foundation.org: use kcalloc()]
Link: http://lkml.kernel.org/r/151068939435.7446.13560129395419350737.stgit@dwillia2-desk3.amr.corp.intel.com
Fixes: 3565fce3a659 ("mm, x86: get_user_pages() for dax mappings")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Suggested-by: Christoph Hellwig <hch@lst.de>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Hal Rosenstock <hal.rosenstock@gmail.com>
Cc: Inki Dae <inki.dae@samsung.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Joonyoung Shim <jy0922.shim@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Sean Hefty <sean.hefty@intel.com>
Cc: Seung-Woo Kim <sw0312.kim@samsung.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/dax.h | 5 ----
include/linux/fs.h | 20 ++++++++++++++++
include/linux/mm.h | 13 ++++++++++
mm/gup.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 97 insertions(+), 5 deletions(-)
--- a/include/linux/dax.h
+++ b/include/linux/dax.h
@@ -61,11 +61,6 @@ static inline int dax_pmd_fault(struct v
int dax_pfn_mkwrite(struct vm_area_struct *, struct vm_fault *);
#define dax_mkwrite(vma, vmf, gb) dax_fault(vma, vmf, gb)
-static inline bool vma_is_dax(struct vm_area_struct *vma)
-{
- return vma->vm_file && IS_DAX(vma->vm_file->f_mapping->host);
-}
-
static inline bool dax_mapping(struct address_space *mapping)
{
return mapping->host && IS_DAX(mapping->host);
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -18,6 +18,7 @@
#include <linux/bug.h>
#include <linux/mutex.h>
#include <linux/rwsem.h>
+#include <linux/mm_types.h>
#include <linux/capability.h>
#include <linux/semaphore.h>
#include <linux/fiemap.h>
@@ -3033,6 +3034,25 @@ static inline bool io_is_direct(struct f
return (filp->f_flags & O_DIRECT) || IS_DAX(filp->f_mapping->host);
}
+static inline bool vma_is_dax(struct vm_area_struct *vma)
+{
+ return vma->vm_file && IS_DAX(vma->vm_file->f_mapping->host);
+}
+
+static inline bool vma_is_fsdax(struct vm_area_struct *vma)
+{
+ struct inode *inode;
+
+ if (!vma->vm_file)
+ return false;
+ if (!vma_is_dax(vma))
+ return false;
+ inode = file_inode(vma->vm_file);
+ if (inode->i_mode == S_IFCHR)
+ return false; /* device-dax */
+ return true;
+}
+
static inline int iocb_flags(struct file *file)
{
int res = 0;
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1288,6 +1288,19 @@ long __get_user_pages_unlocked(struct ta
struct page **pages, unsigned int gup_flags);
long get_user_pages_unlocked(unsigned long start, unsigned long nr_pages,
struct page **pages, unsigned int gup_flags);
+#ifdef CONFIG_FS_DAX
+long get_user_pages_longterm(unsigned long start, unsigned long nr_pages,
+ unsigned int gup_flags, struct page **pages,
+ struct vm_area_struct **vmas);
+#else
+static inline long get_user_pages_longterm(unsigned long start,
+ unsigned long nr_pages, unsigned int gup_flags,
+ struct page **pages, struct vm_area_struct **vmas)
+{
+ return get_user_pages(start, nr_pages, gup_flags, pages, vmas);
+}
+#endif /* CONFIG_FS_DAX */
+
int get_user_pages_fast(unsigned long start, int nr_pages, int write,
struct page **pages);
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -982,6 +982,70 @@ long get_user_pages(unsigned long start,
}
EXPORT_SYMBOL(get_user_pages);
+#ifdef CONFIG_FS_DAX
+/*
+ * This is the same as get_user_pages() in that it assumes we are
+ * operating on the current task's mm, but it goes further to validate
+ * that the vmas associated with the address range are suitable for
+ * longterm elevated page reference counts. For example, filesystem-dax
+ * mappings are subject to the lifetime enforced by the filesystem and
+ * we need guarantees that longterm users like RDMA and V4L2 only
+ * establish mappings that have a kernel enforced revocation mechanism.
+ *
+ * "longterm" == userspace controlled elevated page count lifetime.
+ * Contrast this to iov_iter_get_pages() usages which are transient.
+ */
+long get_user_pages_longterm(unsigned long start, unsigned long nr_pages,
+ unsigned int gup_flags, struct page **pages,
+ struct vm_area_struct **vmas_arg)
+{
+ struct vm_area_struct **vmas = vmas_arg;
+ struct vm_area_struct *vma_prev = NULL;
+ long rc, i;
+
+ if (!pages)
+ return -EINVAL;
+
+ if (!vmas) {
+ vmas = kcalloc(nr_pages, sizeof(struct vm_area_struct *),
+ GFP_KERNEL);
+ if (!vmas)
+ return -ENOMEM;
+ }
+
+ rc = get_user_pages(start, nr_pages, gup_flags, pages, vmas);
+
+ for (i = 0; i < rc; i++) {
+ struct vm_area_struct *vma = vmas[i];
+
+ if (vma == vma_prev)
+ continue;
+
+ vma_prev = vma;
+
+ if (vma_is_fsdax(vma))
+ break;
+ }
+
+ /*
+ * Either get_user_pages() failed, or the vma validation
+ * succeeded, in either case we don't need to put_page() before
+ * returning.
+ */
+ if (i >= rc)
+ goto out;
+
+ for (i = 0; i < rc; i++)
+ put_page(pages[i]);
+ rc = -EOPNOTSUPP;
+out:
+ if (vmas != vmas_arg)
+ kfree(vmas);
+ return rc;
+}
+EXPORT_SYMBOL(get_user_pages_longterm);
+#endif /* CONFIG_FS_DAX */
+
/**
* populate_vma_page_range() - populate a range of pages in the vma.
* @vma: target vma
next prev parent reply other threads:[~2018-02-26 20:20 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-26 20:20 [PATCH 4.9 00/39] 4.9.85-stable review Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 01/39] netfilter: drop outermost socket lock in getsockopt() Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 02/39] xtensa: fix high memory/reserved memory collision Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 03/39] scsi: ibmvfc: fix misdefined reserved field in ibmvfc_fcp_rsp_info Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 04/39] cfg80211: fix cfg80211_beacon_dup Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 05/39] X.509: fix BUG_ON() when hash algorithm is unsupported Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 06/39] PKCS#7: fix certificate chain verification Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 07/39] RDMA/uverbs: Protect from command mask overflow Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 08/39] iio: buffer: check if a buffer has been set up when poll is called Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 09/39] iio: adis_lib: Initialize trigger before requesting interrupt Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 10/39] x86/oprofile: Fix bogus GCC-8 warning in nmi_setup() Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 11/39] irqchip/gic-v3: Use wmb() instead of smb_wmb() in gic_raise_softirq() Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 12/39] PCI/cxgb4: Extend T3 PCI quirk to T4+ devices Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 13/39] ohci-hcd: Fix race condition caused by ohci_urb_enqueue() and io_watchdog_func() Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 14/39] usb: ohci: Proper handling of ed_rm_list to handle race condition between usb_kill_urb() and finish_unlinks() Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 15/39] arm64: Disable unhandled signal log messages by default Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 16/39] Add delay-init quirk for Corsair K70 RGB keyboards Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 17/39] drm/edid: Add 6 bpc quirk for CPT panel in Asus UX303LA Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 18/39] usb: dwc3: gadget: Set maxpacket size for ep0 IN Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 19/39] usb: ldusb: add PIDs for new CASSY devices supported by this driver Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 20/39] Revert "usb: musb: host: dont start next rx urb if current one failed" Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 21/39] usb: gadget: f_fs: Process all descriptors during bind Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 22/39] usb: renesas_usbhs: missed the "running" flag in usb_dmac with rx path Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 23/39] drm/amdgpu: Add dpm quirk for Jet PRO (v2) Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 24/39] drm/amdgpu: add atpx quirk handling (v2) Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 25/39] drm/amdgpu: Avoid leaking PM domain on driver unbind (v2) Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 26/39] drm/amdgpu: add new device to use atpx quirk Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 27/39] binder: add missing binder_unlock() Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 28/39] X.509: fix NULL dereference when restricting key with unsupported_sig Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 29/39] mm: avoid spurious bad pmd warning messages Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 30/39] fs/dax.c: fix inefficiency in dax_writeback_mapping_range() Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 31/39] libnvdimm: fix integer overflow static analysis warning Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 32/39] device-dax: implement ->split() to catch invalid munmap attempts Greg Kroah-Hartman
2018-02-26 20:20 ` Greg Kroah-Hartman [this message]
2018-02-26 20:20 ` [PATCH 4.9 34/39] v4l2: disable filesystem-dax mapping support Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 35/39] IB/core: disable memory registration of filesystem-dax vmas Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 36/39] libnvdimm, dax: fix 1GB-aligned namespaces vs physical misalignment Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 37/39] mm: Fix devm_memremap_pages() collision handling Greg Kroah-Hartman
2018-02-26 20:20 ` [PATCH 4.9 38/39] mm: fail get_vaddr_frames() for filesystem-dax mappings Greg Kroah-Hartman
2018-02-26 20:21 ` [PATCH 4.9 39/39] x86/entry/64: Clear extra registers beyond syscall arguments, to reduce speculation attack surface Greg Kroah-Hartman
2018-02-27 0:57 ` [PATCH 4.9 00/39] 4.9.85-stable review Shuah Khan
2018-02-27 7:12 ` Naresh Kamboju
2018-02-27 14:56 ` Guenter Roeck
2018-02-27 18:34 ` Greg Kroah-Hartman
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