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Message-ID: <0b1cefb4e4021e95902d08c7a43a3033d1e3a4d9.1757534913.git.lorenzo.stoakes@oracle.com>
Date: Wed, 10 Sep 2025 21:22:08 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Jonathan Corbet <corbet@....net>, Matthew Wilcox <willy@...radead.org>,
Guo Ren <guoren@...nel.org>,
Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
Heiko Carstens <hca@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>,
Alexander Gordeev <agordeev@...ux.ibm.com>,
Christian Borntraeger <borntraeger@...ux.ibm.com>,
Sven Schnelle <svens@...ux.ibm.com>,
"David S . Miller" <davem@...emloft.net>,
Andreas Larsson <andreas@...sler.com>, Arnd Bergmann <arnd@...db.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Dan Williams <dan.j.williams@...el.com>,
Vishal Verma <vishal.l.verma@...el.com>,
Dave Jiang <dave.jiang@...el.com>, Nicolas Pitre <nico@...xnic.net>,
Muchun Song <muchun.song@...ux.dev>,
Oscar Salvador <osalvador@...e.de>,
David Hildenbrand <david@...hat.com>,
Konstantin Komarov <almaz.alexandrovich@...agon-software.com>,
Baoquan He <bhe@...hat.com>, Vivek Goyal <vgoyal@...hat.com>,
Dave Young <dyoung@...hat.com>, Tony Luck <tony.luck@...el.com>,
Reinette Chatre <reinette.chatre@...el.com>,
Dave Martin <Dave.Martin@....com>, James Morse <james.morse@....com>,
Alexander Viro <viro@...iv.linux.org.uk>,
Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
"Liam R . Howlett" <Liam.Howlett@...cle.com>,
Vlastimil Babka <vbabka@...e.cz>, Mike Rapoport <rppt@...nel.org>,
Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>,
Hugh Dickins <hughd@...gle.com>,
Baolin Wang <baolin.wang@...ux.alibaba.com>,
Uladzislau Rezki <urezki@...il.com>,
Dmitry Vyukov <dvyukov@...gle.com>,
Andrey Konovalov <andreyknvl@...il.com>, Jann Horn <jannh@...gle.com>,
Pedro Falcato <pfalcato@...e.de>, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-csky@...r.kernel.org, linux-mips@...r.kernel.org,
linux-s390@...r.kernel.org, sparclinux@...r.kernel.org,
nvdimm@...ts.linux.dev, linux-cxl@...r.kernel.org, linux-mm@...ck.org,
ntfs3@...ts.linux.dev, kexec@...ts.infradead.org,
kasan-dev@...glegroups.com, Jason Gunthorpe <jgg@...dia.com>
Subject: [PATCH v2 13/16] mm: update cramfs to use mmap_prepare
cramfs uses either a PFN remap or a mixedmap insertion, we are able to
determine this at the point of mmap_prepare and to select the appropriate
action to perform using the vm_area_desc.
Note that there appears to have been a bug in this code, with the physical
address being specified as the PFN (!!) to vmf_insert_mixed(). This patch
fixes this issue.
Finally, we trivially have to update the pr_debug() message indicating
what's happening to occur before the remap/mixedmap occurs.
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
---
fs/cramfs/inode.c | 46 ++++++++++++++++++++--------------------------
1 file changed, 20 insertions(+), 26 deletions(-)
diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c
index b002e9b734f9..2a41b30753a7 100644
--- a/fs/cramfs/inode.c
+++ b/fs/cramfs/inode.c
@@ -342,16 +342,17 @@ static bool cramfs_last_page_is_shared(struct inode *inode)
return memchr_inv(tail_data, 0, PAGE_SIZE - partial) ? true : false;
}
-static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
+static int cramfs_physmem_mmap_prepare(struct vm_area_desc *desc)
{
+ struct file *file = desc->file;
struct inode *inode = file_inode(file);
struct cramfs_sb_info *sbi = CRAMFS_SB(inode->i_sb);
unsigned int pages, max_pages, offset;
- unsigned long address, pgoff = vma->vm_pgoff;
+ unsigned long address, pgoff = desc->pgoff;
char *bailout_reason;
int ret;
- ret = generic_file_readonly_mmap(file, vma);
+ ret = generic_file_readonly_mmap_prepare(desc);
if (ret)
return ret;
@@ -362,14 +363,14 @@ static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
/* Could COW work here? */
bailout_reason = "vma is writable";
- if (vma->vm_flags & VM_WRITE)
+ if (desc->vm_flags & VM_WRITE)
goto bailout;
max_pages = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
bailout_reason = "beyond file limit";
if (pgoff >= max_pages)
goto bailout;
- pages = min(vma_pages(vma), max_pages - pgoff);
+ pages = min(vma_desc_pages(desc), max_pages - pgoff);
offset = cramfs_get_block_range(inode, pgoff, &pages);
bailout_reason = "unsuitable block layout";
@@ -391,38 +392,31 @@ static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
goto bailout;
}
- if (pages == vma_pages(vma)) {
+ pr_debug("mapping %pD[%lu] at 0x%08lx (%u/%lu pages) "
+ "to vma 0x%08lx, page_prot 0x%llx\n", file,
+ pgoff, address, pages, vma_desc_pages(desc), desc->start,
+ (unsigned long long)pgprot_val(desc->page_prot));
+
+ if (pages == vma_desc_pages(desc)) {
/*
* The entire vma is mappable. remap_pfn_range() will
* make it distinguishable from a non-direct mapping
* in /proc/<pid>/maps by substituting the file offset
* with the actual physical address.
*/
- ret = remap_pfn_range(vma, vma->vm_start, address >> PAGE_SHIFT,
- pages * PAGE_SIZE, vma->vm_page_prot);
+ mmap_action_remap(&desc->action, desc->start,
+ address >> PAGE_SHIFT, pages * PAGE_SIZE,
+ desc->page_prot);
} else {
/*
* Let's create a mixed map if we can't map it all.
* The normal paging machinery will take care of the
* unpopulated ptes via cramfs_read_folio().
*/
- int i;
- vm_flags_set(vma, VM_MIXEDMAP);
- for (i = 0; i < pages && !ret; i++) {
- vm_fault_t vmf;
- unsigned long off = i * PAGE_SIZE;
- vmf = vmf_insert_mixed(vma, vma->vm_start + off,
- address + off);
- if (vmf & VM_FAULT_ERROR)
- ret = vm_fault_to_errno(vmf, 0);
- }
+ mmap_action_mixedmap(&desc->action, desc->start,
+ address >> PAGE_SHIFT, pages);
}
- if (!ret)
- pr_debug("mapped %pD[%lu] at 0x%08lx (%u/%lu pages) "
- "to vma 0x%08lx, page_prot 0x%llx\n", file,
- pgoff, address, pages, vma_pages(vma), vma->vm_start,
- (unsigned long long)pgprot_val(vma->vm_page_prot));
return ret;
bailout:
@@ -434,9 +428,9 @@ static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
#else /* CONFIG_MMU */
-static int cramfs_physmem_mmap(struct file *file, struct vm_area_struct *vma)
+static int cramfs_physmem_mmap_prepare(struct vm_area_desc *desc)
{
- return is_nommu_shared_mapping(vma->vm_flags) ? 0 : -ENOSYS;
+ return is_nommu_shared_mapping(desc->vm_flags) ? 0 : -ENOSYS;
}
static unsigned long cramfs_physmem_get_unmapped_area(struct file *file,
@@ -474,7 +468,7 @@ static const struct file_operations cramfs_physmem_fops = {
.llseek = generic_file_llseek,
.read_iter = generic_file_read_iter,
.splice_read = filemap_splice_read,
- .mmap = cramfs_physmem_mmap,
+ .mmap_prepare = cramfs_physmem_mmap_prepare,
#ifndef CONFIG_MMU
.get_unmapped_area = cramfs_physmem_get_unmapped_area,
.mmap_capabilities = cramfs_physmem_mmap_capabilities,
--
2.51.0
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