[PATCH v4 1/5] mm: add mkwrite param to vm_insert_mixed()
From: Ross Zwisler <hidden>
Date: 2017-07-21 22:39:51
Also in:
dri-devel, linux-arm-msm, linux-ext4, linux-fsdevel, linux-mm, linux-samsung-soc, linux-xfs, lkml, nvdimm
Subsystem:
device direct access (dax), drm driver for qualcomm display hardware, drm drivers, drm drivers and misc gpu patches, drm drivers for exynos, drm drivers for gma500 (poulsbo, moorestown and derivative chipsets), drm drivers for ti omap, drm ttm subsystem, filesystem direct access (dax), filesystems (vfs and infrastructure), memory management, memory management - core, the rest · Maintainers:
Dan Williams, Vishal Verma, Dave Jiang, Rob Clark, Dmitry Baryshkov, David Airlie, Simona Vetter, Maarten Lankhorst, Maxime Ripard, Thomas Zimmermann, Inki Dae, Seung-Woo Kim, Kyungmin Park, Patrik Jakobsson, Tomi Valkeinen, Christian Koenig, Huang Rui, Alexander Viro, Christian Brauner, Andrew Morton, David Hildenbrand, Linus Torvalds
To be able to use the common 4k zero page in DAX we need to have our PTE fault path look more like our PMD fault path where a PTE entry can be marked as dirty and writeable as it is first inserted, rather than waiting for a follow-up dax_pfn_mkwrite() => finish_mkwrite_fault() call. Right now we can rely on having a dax_pfn_mkwrite() call because we can distinguish between these two cases in do_wp_page(): case 1: 4k zero page => writable DAX storage case 2: read-only DAX storage => writeable DAX storage This distinction is made by via vm_normal_page(). vm_normal_page() returns false for the common 4k zero page, though, just as it does for DAX ptes. Instead of special casing the DAX + 4k zero page case, we will simplify our DAX PTE page fault sequence so that it matches our DAX PMD sequence, and get rid of the dax_pfn_mkwrite() helper. We will instead use dax_iomap_fault() to handle write-protection faults. This means that insert_pfn() needs to follow the lead of insert_pfn_pmd() and allow us to pass in a 'mkwrite' flag. If 'mkwrite' is set insert_pfn() will do the work that was previously done by wp_page_reuse() as part of the dax_pfn_mkwrite() call path. Signed-off-by: Ross Zwisler <redacted> --- drivers/dax/device.c | 2 +- drivers/gpu/drm/exynos/exynos_drm_gem.c | 3 ++- drivers/gpu/drm/gma500/framebuffer.c | 2 +- drivers/gpu/drm/msm/msm_gem.c | 3 ++- drivers/gpu/drm/omapdrm/omap_gem.c | 6 ++++-- drivers/gpu/drm/ttm/ttm_bo_vm.c | 2 +- fs/dax.c | 2 +- include/linux/mm.h | 2 +- mm/memory.c | 27 +++++++++++++++++++++------ 9 files changed, 34 insertions(+), 15 deletions(-)
diff --git a/drivers/dax/device.c b/drivers/dax/device.c
index e9f3b3e..3973521 100644
--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c@@ -273,7 +273,7 @@ static int __dev_dax_pte_fault(struct dev_dax *dev_dax, struct vm_fault *vmf) pfn = phys_to_pfn_t(phys, dax_region->pfn_flags); - rc = vm_insert_mixed(vmf->vma, vmf->address, pfn); + rc = vm_insert_mixed(vmf->vma, vmf->address, pfn, false); if (rc == -ENOMEM) return VM_FAULT_OOM;
diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c
index c23479b..bfa6648 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c@@ -466,7 +466,8 @@ int exynos_drm_gem_fault(struct vm_fault *vmf) } pfn = page_to_pfn(exynos_gem->pages[page_offset]); - ret = vm_insert_mixed(vma, vmf->address, __pfn_to_pfn_t(pfn, PFN_DEV)); + ret = vm_insert_mixed(vma, vmf->address, __pfn_to_pfn_t(pfn, PFN_DEV), + false); out: switch (ret) {
diff --git a/drivers/gpu/drm/gma500/framebuffer.c b/drivers/gpu/drm/gma500/framebuffer.c
index 7da70b6..6dd865f 100644
--- a/drivers/gpu/drm/gma500/framebuffer.c
+++ b/drivers/gpu/drm/gma500/framebuffer.c@@ -134,7 +134,7 @@ static int psbfb_vm_fault(struct vm_fault *vmf) pfn = (phys_addr >> PAGE_SHIFT); ret = vm_insert_mixed(vma, address, - __pfn_to_pfn_t(pfn, PFN_DEV)); + __pfn_to_pfn_t(pfn, PFN_DEV), false); if (unlikely((ret == -EBUSY) || (ret != 0 && i > 0))) break; else if (unlikely(ret != 0)) {
diff --git a/drivers/gpu/drm/msm/msm_gem.c b/drivers/gpu/drm/msm/msm_gem.c
index 65f3554..c187fd1 100644
--- a/drivers/gpu/drm/msm/msm_gem.c
+++ b/drivers/gpu/drm/msm/msm_gem.c@@ -249,7 +249,8 @@ int msm_gem_fault(struct vm_fault *vmf) VERB("Inserting %p pfn %lx, pa %lx", (void *)vmf->address, pfn, pfn << PAGE_SHIFT); - ret = vm_insert_mixed(vma, vmf->address, __pfn_to_pfn_t(pfn, PFN_DEV)); + ret = vm_insert_mixed(vma, vmf->address, __pfn_to_pfn_t(pfn, PFN_DEV), + false); out_unlock: mutex_unlock(&msm_obj->lock);
diff --git a/drivers/gpu/drm/omapdrm/omap_gem.c b/drivers/gpu/drm/omapdrm/omap_gem.c
index 5c5c86d..26eebcd 100644
--- a/drivers/gpu/drm/omapdrm/omap_gem.c
+++ b/drivers/gpu/drm/omapdrm/omap_gem.c@@ -393,7 +393,8 @@ static int fault_1d(struct drm_gem_object *obj, VERB("Inserting %p pfn %lx, pa %lx", (void *)vmf->address, pfn, pfn << PAGE_SHIFT); - return vm_insert_mixed(vma, vmf->address, __pfn_to_pfn_t(pfn, PFN_DEV)); + return vm_insert_mixed(vma, vmf->address, __pfn_to_pfn_t(pfn, PFN_DEV), + false); } /* Special handling for the case of faulting in 2d tiled buffers */
@@ -486,7 +487,8 @@ static int fault_2d(struct drm_gem_object *obj, pfn, pfn << PAGE_SHIFT); for (i = n; i > 0; i--) { - vm_insert_mixed(vma, vaddr, __pfn_to_pfn_t(pfn, PFN_DEV)); + vm_insert_mixed(vma, vaddr, __pfn_to_pfn_t(pfn, PFN_DEV), + false); pfn += priv->usergart[fmt].stride_pfn; vaddr += PAGE_SIZE * m; }
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index b442d12..e85bfa7 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c@@ -248,7 +248,7 @@ static int ttm_bo_vm_fault(struct vm_fault *vmf) if (vma->vm_flags & VM_MIXEDMAP) ret = vm_insert_mixed(&cvma, address, - __pfn_to_pfn_t(pfn, PFN_DEV)); + __pfn_to_pfn_t(pfn, PFN_DEV), false); else ret = vm_insert_pfn(&cvma, address, pfn);
diff --git a/fs/dax.c b/fs/dax.c
index 306c2b6..c844a51 100644
--- a/fs/dax.c
+++ b/fs/dax.c@@ -899,7 +899,7 @@ static int dax_insert_mapping(struct address_space *mapping, *entryp = ret; trace_dax_insert_mapping(mapping->host, vmf, ret); - return vm_insert_mixed(vma, vaddr, pfn); + return vm_insert_mixed(vma, vaddr, pfn, false); } /**
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 46b9ac5..3eabc40 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -2292,7 +2292,7 @@ int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr, int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr, unsigned long pfn, pgprot_t pgprot); int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, - pfn_t pfn); + pfn_t pfn, bool mkwrite); int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
diff --git a/mm/memory.c b/mm/memory.c
index 0e517be..d351911 100644
--- a/mm/memory.c
+++ b/mm/memory.c@@ -1646,7 +1646,7 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, EXPORT_SYMBOL(vm_insert_page); static int insert_pfn(struct vm_area_struct *vma, unsigned long addr, - pfn_t pfn, pgprot_t prot) + pfn_t pfn, pgprot_t prot, bool mkwrite) { struct mm_struct *mm = vma->vm_mm; int retval;
@@ -1658,14 +1658,28 @@ static int insert_pfn(struct vm_area_struct *vma, unsigned long addr, if (!pte) goto out; retval = -EBUSY; - if (!pte_none(*pte)) - goto out_unlock; + if (!pte_none(*pte)) { + if (mkwrite) { + if (WARN_ON_ONCE(pte_pfn(*pte) != pfn_t_to_pfn(pfn))) + goto out_unlock; + entry = *pte; + goto out_mkwrite; + } else + goto out_unlock; + } /* Ok, finally just insert the thing.. */ if (pfn_t_devmap(pfn)) entry = pte_mkdevmap(pfn_t_pte(pfn, prot)); else entry = pte_mkspecial(pfn_t_pte(pfn, prot)); + +out_mkwrite: + if (mkwrite) { + entry = pte_mkyoung(entry); + entry = maybe_mkwrite(pte_mkdirty(entry), vma); + } + set_pte_at(mm, addr, pte, entry); update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
@@ -1736,14 +1750,15 @@ int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr, track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV)); - ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot); + ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot, + false); return ret; } EXPORT_SYMBOL(vm_insert_pfn_prot); int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, - pfn_t pfn) + pfn_t pfn, bool mkwrite) { pgprot_t pgprot = vma->vm_page_prot;
@@ -1772,7 +1787,7 @@ int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr, page = pfn_to_page(pfn_t_to_pfn(pfn)); return insert_page(vma, addr, page, pgprot); } - return insert_pfn(vma, addr, pfn, pgprot); + return insert_pfn(vma, addr, pfn, pgprot, mkwrite); } EXPORT_SYMBOL(vm_insert_mixed);
--
2.9.4