similar to: dev_pagemap related cleanups v3

Hi Dan, Jérôme and Jason, below is a series that cleans up the dev_pagemap interface so that it is more easily usable, which removes the need to wrap it in hmm and thus allowing to kill a lot of code Note: this series is on top of the rdma/hmm branch + the dev_pagemap releas fix series from Dan that went into 5.2-rc5. Git tree: git://git.infradead.org/users/hch/misc.git

Hi Dan, Jérôme and Jason, below is a series that cleans up the dev_pagemap interface so that it is more easily usable, which removes the need to wrap it in hmm and thus allowing to kill a lot of code Diffstat: 22 files changed, 245 insertions(+), 802 deletions(-) Git tree: git://git.infradead.org/users/hch/misc.git hmm-devmem-cleanup Gitweb:

When acting on device private mappings a driver needs to know if the device (or other entity in case of kvmppc) actually owns this private mapping. This series adds an owner field and converts the migrate_vma code over to check it. I looked into doing the same for hmm_range_fault, but as far as I can tell that code has never been wired up to actually work for device private memory, so instead of

On 2019-06-13 12:27 p.m., Dan Williams wrote: > On Thu, Jun 13, 2019 at 2:43 AM Christoph Hellwig <hch at lst.de> wrote: >> >> Hi Dan, Jérôme and Jason, >> >> below is a series that cleans up the dev_pagemap interface so that >> it is more easily usable, which removes the need to wrap it in hmm >> and thus allowing to kill a lot of code >>

On Thu, Jun 13, 2019 at 11:43:16AM +0200, Christoph Hellwig wrote: > The functionality is identical to the one currently open coded in > device-dax. > > Signed-off-by: Christoph Hellwig <hch at lst.de> > --- > drivers/dax/dax-private.h | 4 --- > drivers/dax/device.c | 52 +-------------------------------------- > 2 files changed, 1 insertion(+), 55

ZONE_DEVICE struct pages have an extra reference count that complicates the code for put_page() and several places in the kernel that need to check the reference count to see that a page is not being used (gup, compaction, migration, etc.). Clean up the code so the reference count doesn't need to be treated specially for ZONE_DEVICE. Signed-off-by: Ralph Campbell <rcampbell at

The dev_pagemap is a growing too many callbacks. Move them into a separate ops structure so that they are not duplicated for multiple instances, and an attacker can't easily overwrite them. Signed-off-by: Christoph Hellwig <hch at lst.de> Reviewed-by: Logan Gunthorpe <logang at deltatee.com> Reviewed-by: Jason Gunthorpe <jgg at mellanox.com> --- drivers/dax/device.c

On 2019-06-13 2:21 p.m., Dan Williams wrote: > On Thu, Jun 13, 2019 at 1:18 PM Logan Gunthorpe <logang at deltatee.com> wrote: >> >> >> >> On 2019-06-13 12:27 p.m., Dan Williams wrote: >>> On Thu, Jun 13, 2019 at 2:43 AM Christoph Hellwig <hch at lst.de> wrote: >>>> >>>> Hi Dan, Jérôme and Jason, >>>>

On Thu, Jun 13, 2019 at 11:27:39AM -0700, Dan Williams wrote: > On Thu, Jun 13, 2019 at 2:43 AM Christoph Hellwig <hch at lst.de> wrote: > > > > Hi Dan, Jérôme and Jason, > > > > below is a series that cleans up the dev_pagemap interface so that > > it is more easily usable, which removes the need to wrap it in hmm > > and thus allowing to kill a lot of

This is still an RFC because after looking at the pmem/dax code some more, I realized that the ZONE_DEVICE struct pages are being inserted into the process' page tables with vmf_insert_mixed() and a zero refcount on the ZONE_DEVICE struct page. This is sort of OK because insert_pfn() increments the reference count on the pgmap which is what prevents memunmap_pages() from freeing the struct

On Wed, Jun 26, 2019 at 02:27:11PM +0200, Christoph Hellwig wrote: > This replaces the hacky ->fault callback, which is currently directly > called from common code through a hmm specific data structure as an > exercise in layering violations. > > Signed-off-by: Christoph Hellwig <hch at lst.de> > Reviewed-by: Ralph Campbell <rcampbell at nvidia.com> > --- >

Matthew Wilcox, Ira Weiny, and others have complained that ZONE_DEVICE struct page reference counting is ugly because they are "free" when the reference count is one instead of zero. This leads to explicit checks for ZONE_DEVICE pages in places like put_page(), GUP, THP splitting, and page migration which have to adjust the expected reference count when determining if the page is

The dev_pagemap is a growing too many callbacks. Move them into a separate ops structure so that they are not duplicated for multiple instances, and an attacker can't easily overwrite them. Signed-off-by: Christoph Hellwig <hch at lst.de> --- drivers/dax/device.c | 6 +++++- drivers/nvdimm/pmem.c | 18 +++++++++++++----- drivers/pci/p2pdma.c | 5

On Wed, Jun 26, 2019 at 02:27:10PM +0200, Christoph Hellwig wrote: > Just check if there is a ->page_free operation set and take care of the > static key enable, as well as the put using device managed resources. > Also check that a ->page_free is provided for the pgmaps types that > require it, and check for a valid type as well while we are at it. > > Note that this also

When acting on device private mappings a driver needs to know if the device (or other entity in case of kvmppc) actually owns this private mapping. This series adds an owner field and converts the migrate_vma code over to check it. I looked into doing the same for hmm_range_fault, but as far as I can tell that code has never been wired up to actually work for device private memory, so instead of

Add a flags field to struct dev_pagemap to replace the altmap_valid boolean to be a little more extensible. Also add a pgmap_altmap() helper to find the optional altmap and clean up the code using the altmap using it. Signed-off-by: Christoph Hellwig <hch at lst.de> --- arch/powerpc/mm/mem.c | 10 +--------- arch/x86/mm/init_64.c | 8 ++------ drivers/nvdimm/pfn_devs.c | 3 +--

struct dev_pagemap is always embedded into a containing structure, so there is no need to an additional private data field. Signed-off-by: Christoph Hellwig <hch at lst.de> --- drivers/nvdimm/pmem.c | 2 +- include/linux/memremap.h | 3 +-- kernel/memremap.c | 2 +- mm/hmm.c | 9 +++++---- 4 files changed, 8 insertions(+), 8 deletions(-) diff --git

This replaces the hacky ->fault callback, which is currently directly called from common code through a hmm specific data structure as an exercise in layering violations. Signed-off-by: Christoph Hellwig <hch at lst.de> Reviewed-by: Ralph Campbell <rcampbell at nvidia.com> --- include/linux/hmm.h | 6 ------ include/linux/memremap.h | 6 ++++++ include/linux/swapops.h | 15

This replaces the hacky ->fault callback, which is currently directly called from common code through a hmm specific data structure as an exercise in layering violations. Signed-off-by: Christoph Hellwig <hch at lst.de> --- include/linux/hmm.h | 6 ------ include/linux/memremap.h | 6 ++++++ include/linux/swapops.h | 15 --------------- kernel/memremap.c | 31

On 6/13/19 2:43 AM, Christoph Hellwig wrote: > This replaces the hacky ->fault callback, which is currently directly > called from common code through a hmm specific data structure as an > exercise in layering violations. > > Signed-off-by: Christoph Hellwig <hch at lst.de> > --- > include/linux/hmm.h | 6 ------ > include/linux/memremap.h | 6 ++++++