similar to: [PATCHv4 1/2] mm: export use_mm/unuse_mm to modules

vhost net module wants to do copy to/from user from a kernel thread, which needs use_mm (like what fs/aio has). Move that into mm/ and export to modules. Acked-by: Andrew Morton <akpm at linux-foundation.org> Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- fs/aio.c | 47 +---------------------------------- include/linux/mmu_context.h | 9 ++++++

vhost net module wants to do copy to/from user from a kernel thread, which needs use_mm (like what fs/aio has). Move that into mm/ and export to modules. Acked-by: Andrew Morton <akpm at linux-foundation.org> Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- fs/aio.c | 47 +---------------------------------- include/linux/mmu_context.h | 9 ++++++

vhost net module wants to do copy to/from user from a kernel thread, which needs use_mm (like what fs/aio has). Move that into mm/ and export to modules. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- fs/aio.c | 47 +---------------------------------- include/linux/mmu_context.h | 9 ++++++ mm/Makefile | 2 +- mm/mmu_context.c

vhost net module wants to do copy to/from user from a kernel thread, which needs use_mm (like what fs/aio has). Move that into mm/ and export to modules. Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- fs/aio.c | 47 +---------------------------------- include/linux/mmu_context.h | 9 ++++++ mm/Makefile | 2 +- mm/mmu_context.c

Anyone who wants to do copy to/from user from a kernel thread, needs use_mm (like what fs/aio has). Move that into mm/, to make reusing and exporting easier down the line, and make aio use it. Next intended user, besides aio, will be vhost-net. Acked-by: Andrea Arcangeli <aarcange at redhat.com> Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- fs/aio.c |

Anyone who wants to do copy to/from user from a kernel thread, needs use_mm (like what fs/aio has). Move that into mm/, to make reusing and exporting easier down the line, and make aio use it. Next intended user, besides aio, will be vhost-net. Acked-by: Andrea Arcangeli <aarcange at redhat.com> Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- fs/aio.c |

vhost net module wants to do copy to/from user from a kernel thread, which needs use_mm (like what fs/aio has). Move that into mm/ and export to modules. Acked-by: Andrew Morton <akpm at linux-foundation.org> Acked-by: Andrea Arcangeli <aarcange at redhat.com> Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- fs/aio.c | 47

vhost net module wants to do copy to/from user from a kernel thread, which needs use_mm (like what fs/aio has). Move that into mm/ and export to modules. Acked-by: Andrew Morton <akpm at linux-foundation.org> Acked-by: Andrea Arcangeli <aarcange at redhat.com> Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- fs/aio.c | 47

These helpers are only for use with kernel threads, and I will tie them more into the kthread infrastructure going forward. Also move the prototypes to kthread.h - mmu_context.h was a little weird to start with as it otherwise contains very low-level MM bits. Signed-off-by: Christoph Hellwig <hch at lst.de> --- drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h | 1 +

Switch the function documentation to kerneldoc comments, and add WARN_ON_ONCE asserts that the calling thread is a kernel thread and does not have ->mm set (or has ->mm set in the case of unuse_mm). Also give the functions a kthread_ prefix to better document the use case. Signed-off-by: Christoph Hellwig <hch at lst.de> --- drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h | 4 +--

Switch the function documentation to kerneldoc comments, and add WARN_ON_ONCE asserts that the calling thread is a kernel thread and does not have ->mm set (or has ->mm set in the case of unuse_mm). Also give the functions a kthread_ prefix to better document the use case. Signed-off-by: Christoph Hellwig <hch at lst.de> Acked-by: Felix Kuehling <Felix.Kuehling at amd.com> ---

When mm switched to matches that of active mm, we don't need to increment and then drop the mm count. Making that conditional reduces contention on that cache line on SMP systems. Acked-by: Andrea Arcangeli <aarcange at redhat.com> Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- mm/mmu_context.c | 9 ++++++--- 1 files changed, 6 insertions(+), 3 deletions(-) diff

When mm switched to matches that of active mm, we don't need to increment and then drop the mm count. Making that conditional reduces contention on that cache line on SMP systems. Acked-by: Andrea Arcangeli <aarcange at redhat.com> Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- mm/mmu_context.c | 9 ++++++--- 1 files changed, 6 insertions(+), 3 deletions(-) diff

When mm switched to matches that of active mm, we don't need to increment and then drop the mm count. In a simple benchmark this happens in about 50% of time. Making that conditional reduces contention on that cache line on SMP systems. Acked-by: Andrea Arcangeli <aarcange at redhat.com> Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- mm/mmu_context.c | 9 ++++++---

When mm switched to matches that of active mm, we don't need to increment and then drop the mm count. In a simple benchmark this happens in about 50% of time. Making that conditional reduces contention on that cache line on SMP systems. Acked-by: Andrea Arcangeli <aarcange at redhat.com> Signed-off-by: Michael S. Tsirkin <mst at redhat.com> --- mm/mmu_context.c | 9 ++++++---

Hi all, this series improves the use_mm / unuse_mm interface by better documenting the assumptions, and my taking the set_fs manipulations spread over the callers into the core API. Changes since v1: - drop a few patches - fix a comment typo - cover the newly merged use_mm/unuse_mm caller in vfio

Hi all, this series improves the use_mm / unuse_mm interface by better documenting the assumptions, and my taking the set_fs manipulations spread over the callers into the core API. Changes since v1: - drop a few patches - fix a comment typo - cover the newly merged use_mm/unuse_mm caller in vfio

Hi all, this series improves the use_mm / unuse_mm interface by better documenting the assumptions, and my taking the set_fs manipulations spread over the callers into the core API.

Hi all, this series improves the use_mm / unuse_mm interface by better documenting the assumptions, and my taking the set_fs manipulations spread over the callers into the core API.

Rusty, could you review and comment on the patches please? Since most of the code deals with virtio from host side, I think it will make sense to merge them through your tree. What do you think? One comment on placement: I put files under a separate vhost directory to avoid confusion with virtio-net which runs in guest. Does this sound sane? If not let me know and I'll move them. Thanks!