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Message-Id: <a069644388e6f1593a7020d15840e6fc9f39bcaf.1678661628.git.lstoakes@gmail.com>
Date: Sun, 12 Mar 2023 23:40:13 +0000
From: Lorenzo Stoakes <lstoakes@...il.com>
To: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
dri-devel@...ts.freedesktop.org,
Andrew Morton <akpm@...ux-foundation.org>
Cc: Thomas Hellstrom <thomas.hellstrom@...ux.intel.com>,
Christian Konig <christian.koenig@....com>,
Matthew Wilcox <willy@...radead.org>,
Michal Hocko <mhocko@...e.com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
Dan Williams <dan.j.williams@...el.com>,
Jason Gunthorpe <jgg@...pe.ca>,
Lorenzo Stoakes <lstoakes@...il.com>
Subject: [PATCH 1/3] mm: remove unused vmf_insert_mixed_prot()
The sole user of vmf_insert_mixed_prot(), the drm ttm module, stopped using
this in commit f91142c62161 ("drm/ttm: nuke VM_MIXEDMAP on BO mappings v3")
citing use of VM_MIXEDMAP in this case being terribly broken.
Remove this now-dead code and references to it, but retain the useful
description of the prot != vma->vm_page_prot case, moving it to
vmf_insert_pfn_prot() instead.
Signed-off-by: Lorenzo Stoakes <lstoakes@...il.com>
---
include/linux/mm.h | 2 --
include/linux/mm_types.h | 7 +----
mm/memory.c | 57 +++++++++++++---------------------------
3 files changed, 19 insertions(+), 47 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index ce1590933995..ee755bb4e1c1 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3330,8 +3330,6 @@ vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
unsigned long pfn, pgprot_t pgprot);
vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
pfn_t pfn);
-vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,
- pfn_t pfn, pgprot_t pgprot);
vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
unsigned long addr, pfn_t pfn);
int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 3a028db80ffb..5ef0d0da328a 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -502,12 +502,7 @@ struct vm_area_struct {
};
struct mm_struct *vm_mm; /* The address space we belong to. */
-
- /*
- * Access permissions of this VMA.
- * See vmf_insert_mixed_prot() for discussion.
- */
- pgprot_t vm_page_prot;
+ pgprot_t vm_page_prot; /* Access permissions of this VMA. */
/*
* Flags, see mm.h.
diff --git a/mm/memory.c b/mm/memory.c
index 7ca7951adcf5..ee6bcd747867 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2147,8 +2147,20 @@ static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
* vmf_insert_pfn_prot should only be used if using multiple VMAs is
* impractical.
*
- * See vmf_insert_mixed_prot() for a discussion of the implication of using
- * a value of @pgprot different from that of @vma->vm_page_prot.
+ * pgprot typically only differs from @vma->vm_page_prot when drivers set
+ * caching- and encryption bits different than those of @vma->vm_page_prot,
+ * because the caching- or encryption mode may not be known at mmap() time.
+ *
+ * This is ok as long as @vma->vm_page_prot is not used by the core vm
+ * to set caching and encryption bits for those vmas (except for COW pages).
+ * This is ensured by core vm only modifying these page table entries using
+ * functions that don't touch caching- or encryption bits, using pte_modify()
+ * if needed. (See for example mprotect()).
+ *
+ * Also when new page-table entries are created, this is only done using the
+ * fault() callback, and never using the value of vma->vm_page_prot,
+ * except for page-table entries that point to anonymous pages as the result
+ * of COW.
*
* Context: Process context. May allocate using %GFP_KERNEL.
* Return: vm_fault_t value.
@@ -2223,9 +2235,9 @@ static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
}
static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
- unsigned long addr, pfn_t pfn, pgprot_t pgprot,
- bool mkwrite)
+ unsigned long addr, pfn_t pfn, bool mkwrite)
{
+ pgprot_t pgprot = vma->vm_page_prot;
int err;
BUG_ON(!vm_mixed_ok(vma, pfn));
@@ -2268,43 +2280,10 @@ static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
return VM_FAULT_NOPAGE;
}
-/**
- * vmf_insert_mixed_prot - insert single pfn into user vma with specified pgprot
- * @vma: user vma to map to
- * @addr: target user address of this page
- * @pfn: source kernel pfn
- * @pgprot: pgprot flags for the inserted page
- *
- * This is exactly like vmf_insert_mixed(), except that it allows drivers
- * to override pgprot on a per-page basis.
- *
- * Typically this function should be used by drivers to set caching- and
- * encryption bits different than those of @vma->vm_page_prot, because
- * the caching- or encryption mode may not be known at mmap() time.
- * This is ok as long as @vma->vm_page_prot is not used by the core vm
- * to set caching and encryption bits for those vmas (except for COW pages).
- * This is ensured by core vm only modifying these page table entries using
- * functions that don't touch caching- or encryption bits, using pte_modify()
- * if needed. (See for example mprotect()).
- * Also when new page-table entries are created, this is only done using the
- * fault() callback, and never using the value of vma->vm_page_prot,
- * except for page-table entries that point to anonymous pages as the result
- * of COW.
- *
- * Context: Process context. May allocate using %GFP_KERNEL.
- * Return: vm_fault_t value.
- */
-vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,
- pfn_t pfn, pgprot_t pgprot)
-{
- return __vm_insert_mixed(vma, addr, pfn, pgprot, false);
-}
-EXPORT_SYMBOL(vmf_insert_mixed_prot);
-
vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
pfn_t pfn)
{
- return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, false);
+ return __vm_insert_mixed(vma, addr, pfn, false);
}
EXPORT_SYMBOL(vmf_insert_mixed);
@@ -2316,7 +2295,7 @@ EXPORT_SYMBOL(vmf_insert_mixed);
vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
unsigned long addr, pfn_t pfn)
{
- return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, true);
+ return __vm_insert_mixed(vma, addr, pfn, true);
}
EXPORT_SYMBOL(vmf_insert_mixed_mkwrite);
--
2.39.2
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