From 9ac09bb9feaccc2f45e5606dc48a3f748d478dc4 Mon Sep 17 00:00:00 2001 From: Ryan Roberts Date: Fri, 3 Oct 2025 16:53:04 +0100 Subject: mm: consistently use current->mm in mm_get_unmapped_area() mm_get_unmapped_area() is a wrapper around arch_get_unmapped_area() / arch_get_unmapped_area_topdown(), both of which search current->mm for some free space. Neither take an mm_struct - they implicitly operate on current->mm. But the wrapper takes an mm_struct and uses it to decide whether to search bottom up or top down. All callers pass in current->mm for this, so everything is working consistently. But it feels like an accident waiting to happen; eventually someone will call that function with a different mm, expecting to find free space in it, but what gets returned is free space in the current mm. So let's simplify by removing the parameter and have the wrapper use current->mm to decide which end to start at. Now everything is consistent and self-documenting. Link: https://lkml.kernel.org/r/20251003155306.2147572-1-ryan.roberts@arm.com Signed-off-by: Ryan Roberts Acked-by: David Hildenbrand Reviewed-by: Oscar Salvador Reviewed-by: Dev Jain Reviewed-by: Anshuman Khandual Reviewed-by: Lorenzo Stoakes Reviewed-by: Baolin Wang Cc: Liam Howlett Cc: Michal Hocko Cc: Mike Rapoport Cc: Suren Baghdasaryan Cc: Vlastimil Babka Signed-off-by: Andrew Morton --- drivers/dax/device.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'drivers/dax') diff --git a/drivers/dax/device.c b/drivers/dax/device.c index 2bb40a6060af..7f1ed0db8337 100644 --- a/drivers/dax/device.c +++ b/drivers/dax/device.c @@ -330,14 +330,13 @@ static unsigned long dax_get_unmapped_area(struct file *filp, if ((off + len_align) < off) goto out; - addr_align = mm_get_unmapped_area(current->mm, filp, addr, len_align, - pgoff, flags); + addr_align = mm_get_unmapped_area(filp, addr, len_align, pgoff, flags); if (!IS_ERR_VALUE(addr_align)) { addr_align += (off - addr_align) & (align - 1); return addr_align; } out: - return mm_get_unmapped_area(current->mm, filp, addr, len, pgoff, flags); + return mm_get_unmapped_area(filp, addr, len, pgoff, flags); } static const struct address_space_operations dev_dax_aops = { -- cgit v1.2.3 From 8e18a7f43557f5caea18dfd82a24b6839ab0a956 Mon Sep 17 00:00:00 2001 From: Lorenzo Stoakes Date: Mon, 20 Oct 2025 13:11:19 +0100 Subject: device/dax: update devdax to use mmap_prepare The devdax driver does nothing special in its f_op->mmap hook, so straightforwardly update it to use the mmap_prepare hook instead. Link: https://lkml.kernel.org/r/1e8665d052ac8cf2f7ff92b6c7862614f7fd306c.1760959442.git.lorenzo.stoakes@oracle.com Signed-off-by: Lorenzo Stoakes Acked-by: David Hildenbrand Reviewed-by: Jan Kara Reviewed-by: Jason Gunthorpe Acked-by: Pedro Falcato Cc: Alexander Gordeev Cc: Al Viro Cc: Andreas Larsson Cc: Andrey Konovalov Cc: Arnd Bergmann Cc: Baolin Wang Cc: Baoquan He Cc: Chatre, Reinette Cc: Christian Borntraeger Cc: Christian Brauner Cc: Dan Williams Cc: Dave Jiang Cc: Dave Martin Cc: Dave Young Cc: David S. Miller Cc: Dmitriy Vyukov Cc: Greg Kroah-Hartman Cc: Guo Ren Cc: Heiko Carstens Cc: Hugh Dickins Cc: James Morse Cc: Jann Horn Cc: Jonathan Corbet Cc: Kevin Tian Cc: Konstantin Komarov Cc: Liam Howlett Cc: "Luck, Tony" Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Mike Rapoport Cc: Muchun Song Cc: Nicolas Pitre Cc: Oscar Salvador Cc: Robin Murohy Cc: Sumanth Korikkar Cc: Suren Baghdasaryan Cc: Sven Schnelle Cc: Thomas Bogendoerfer Cc: "Uladzislau Rezki (Sony)" Cc: Vasily Gorbik Cc: Vishal Verma Cc: Vivek Goyal Cc: Vlastimil Babka Cc: Will Deacon Signed-off-by: Andrew Morton --- drivers/dax/device.c | 32 +++++++++++++++++++++----------- 1 file changed, 21 insertions(+), 11 deletions(-) (limited to 'drivers/dax') diff --git a/drivers/dax/device.c b/drivers/dax/device.c index 7f1ed0db8337..22999a402e02 100644 --- a/drivers/dax/device.c +++ b/drivers/dax/device.c @@ -13,8 +13,9 @@ #include "dax-private.h" #include "bus.h" -static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma, - const char *func) +static int __check_vma(struct dev_dax *dev_dax, vm_flags_t vm_flags, + unsigned long start, unsigned long end, struct file *file, + const char *func) { struct device *dev = &dev_dax->dev; unsigned long mask; @@ -23,7 +24,7 @@ static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma, return -ENXIO; /* prevent private mappings from being established */ - if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) { + if ((vm_flags & VM_MAYSHARE) != VM_MAYSHARE) { dev_info_ratelimited(dev, "%s: %s: fail, attempted private mapping\n", current->comm, func); @@ -31,15 +32,15 @@ static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma, } mask = dev_dax->align - 1; - if (vma->vm_start & mask || vma->vm_end & mask) { + if (start & mask || end & mask) { dev_info_ratelimited(dev, "%s: %s: fail, unaligned vma (%#lx - %#lx, %#lx)\n", - current->comm, func, vma->vm_start, vma->vm_end, + current->comm, func, start, end, mask); return -EINVAL; } - if (!vma_is_dax(vma)) { + if (!file_is_dax(file)) { dev_info_ratelimited(dev, "%s: %s: fail, vma is not DAX capable\n", current->comm, func); @@ -49,6 +50,13 @@ static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma, return 0; } +static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma, + const char *func) +{ + return __check_vma(dev_dax, vma->vm_flags, vma->vm_start, vma->vm_end, + vma->vm_file, func); +} + /* see "strong" declaration in tools/testing/nvdimm/dax-dev.c */ __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff, unsigned long size) @@ -285,8 +293,9 @@ static const struct vm_operations_struct dax_vm_ops = { .pagesize = dev_dax_pagesize, }; -static int dax_mmap(struct file *filp, struct vm_area_struct *vma) +static int dax_mmap_prepare(struct vm_area_desc *desc) { + struct file *filp = desc->file; struct dev_dax *dev_dax = filp->private_data; int rc, id; @@ -297,13 +306,14 @@ 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(dev_dax, desc->vm_flags, desc->start, desc->end, filp, + __func__); dax_read_unlock(id); if (rc) return rc; - vma->vm_ops = &dax_vm_ops; - vm_flags_set(vma, VM_HUGEPAGE); + desc->vm_ops = &dax_vm_ops; + desc->vm_flags |= VM_HUGEPAGE; return 0; } @@ -376,7 +386,7 @@ static const struct file_operations dax_fops = { .open = dax_open, .release = dax_release, .get_unmapped_area = dax_get_unmapped_area, - .mmap = dax_mmap, + .mmap_prepare = dax_mmap_prepare, .fop_flags = FOP_MMAP_SYNC, }; -- cgit v1.2.3