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Subject[PATCH 5.1 070/128] mm/huge_memory: fix vmf_insert_pfn_{pmd, pud}() crash, handle unaligned addresses
Date
From: Dan Williams <dan.j.williams@intel.com>

commit fce86ff5802bac3a7b19db171aa1949ef9caac31 upstream.

Starting with c6f3c5ee40c1 ("mm/huge_memory.c: fix modifying of page
protection by insert_pfn_pmd()") vmf_insert_pfn_pmd() internally calls
pmdp_set_access_flags(). That helper enforces a pmd aligned @address
argument via VM_BUG_ON() assertion.

Update the implementation to take a 'struct vm_fault' argument directly
and apply the address alignment fixup internally to fix crash signatures
like:

kernel BUG at arch/x86/mm/pgtable.c:515!
invalid opcode: 0000 [#1] SMP NOPTI
CPU: 51 PID: 43713 Comm: java Tainted: G OE 4.19.35 #1
[..]
RIP: 0010:pmdp_set_access_flags+0x48/0x50
[..]
Call Trace:
vmf_insert_pfn_pmd+0x198/0x350
dax_iomap_fault+0xe82/0x1190
ext4_dax_huge_fault+0x103/0x1f0
? __switch_to_asm+0x40/0x70
__handle_mm_fault+0x3f6/0x1370
? __switch_to_asm+0x34/0x70
? __switch_to_asm+0x40/0x70
handle_mm_fault+0xda/0x200
__do_page_fault+0x249/0x4f0
do_page_fault+0x32/0x110
? page_fault+0x8/0x30
page_fault+0x1e/0x30

Link: http://lkml.kernel.org/r/155741946350.372037.11148198430068238140.stgit@dwillia2-desk3.amr.corp.intel.com
Fixes: c6f3c5ee40c1 ("mm/huge_memory.c: fix modifying of page protection by insert_pfn_pmd()")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: Piotr Balcer <piotr.balcer@intel.com>
Tested-by: Yan Ma <yan.ma@intel.com>
Tested-by: Pankaj Gupta <pagupta@redhat.com>
Reviewed-by: Matthew Wilcox <willy@infradead.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Chandan Rajendra <chandan@linux.ibm.com>
Cc: Souptick Joarder <jrdr.linux@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/dax/device.c | 6 ++----
fs/dax.c | 6 ++----
include/linux/huge_mm.h | 6 ++----
mm/huge_memory.c | 16 ++++++++++------
4 files changed, 16 insertions(+), 18 deletions(-)

--- a/drivers/dax/device.c
+++ b/drivers/dax/device.c
@@ -184,8 +184,7 @@ static vm_fault_t __dev_dax_pmd_fault(st

*pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);

- return vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd, *pfn,
- vmf->flags & FAULT_FLAG_WRITE);
+ return vmf_insert_pfn_pmd(vmf, *pfn, vmf->flags & FAULT_FLAG_WRITE);
}

#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
@@ -235,8 +234,7 @@ static vm_fault_t __dev_dax_pud_fault(st

*pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);

- return vmf_insert_pfn_pud(vmf->vma, vmf->address, vmf->pud, *pfn,
- vmf->flags & FAULT_FLAG_WRITE);
+ return vmf_insert_pfn_pud(vmf, *pfn, vmf->flags & FAULT_FLAG_WRITE);
}
#else
static vm_fault_t __dev_dax_pud_fault(struct dev_dax *dev_dax,
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1575,8 +1575,7 @@ static vm_fault_t dax_iomap_pmd_fault(st
}

trace_dax_pmd_insert_mapping(inode, vmf, PMD_SIZE, pfn, entry);
- result = vmf_insert_pfn_pmd(vma, vmf->address, vmf->pmd, pfn,
- write);
+ result = vmf_insert_pfn_pmd(vmf, pfn, write);
break;
case IOMAP_UNWRITTEN:
case IOMAP_HOLE:
@@ -1686,8 +1685,7 @@ dax_insert_pfn_mkwrite(struct vm_fault *
ret = vmf_insert_mixed_mkwrite(vmf->vma, vmf->address, pfn);
#ifdef CONFIG_FS_DAX_PMD
else if (order == PMD_ORDER)
- ret = vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd,
- pfn, true);
+ ret = vmf_insert_pfn_pmd(vmf, pfn, FAULT_FLAG_WRITE);
#endif
else
ret = VM_FAULT_FALLBACK;
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -47,10 +47,8 @@ extern bool move_huge_pmd(struct vm_area
extern int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
unsigned long addr, pgprot_t newprot,
int prot_numa);
-vm_fault_t vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
- pmd_t *pmd, pfn_t pfn, bool write);
-vm_fault_t vmf_insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
- pud_t *pud, pfn_t pfn, bool write);
+vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write);
+vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write);
enum transparent_hugepage_flag {
TRANSPARENT_HUGEPAGE_FLAG,
TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -793,11 +793,13 @@ out_unlock:
pte_free(mm, pgtable);
}

-vm_fault_t vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
- pmd_t *pmd, pfn_t pfn, bool write)
+vm_fault_t vmf_insert_pfn_pmd(struct vm_fault *vmf, pfn_t pfn, bool write)
{
+ unsigned long addr = vmf->address & PMD_MASK;
+ struct vm_area_struct *vma = vmf->vma;
pgprot_t pgprot = vma->vm_page_prot;
pgtable_t pgtable = NULL;
+
/*
* If we had pmd_special, we could avoid all these restrictions,
* but we need to be consistent with PTEs and architectures that
@@ -820,7 +822,7 @@ vm_fault_t vmf_insert_pfn_pmd(struct vm_

track_pfn_insert(vma, &pgprot, pfn);

- insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write, pgtable);
+ insert_pfn_pmd(vma, addr, vmf->pmd, pfn, pgprot, write, pgtable);
return VM_FAULT_NOPAGE;
}
EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);
@@ -869,10 +871,12 @@ out_unlock:
spin_unlock(ptl);
}

-vm_fault_t vmf_insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
- pud_t *pud, pfn_t pfn, bool write)
+vm_fault_t vmf_insert_pfn_pud(struct vm_fault *vmf, pfn_t pfn, bool write)
{
+ unsigned long addr = vmf->address & PUD_MASK;
+ struct vm_area_struct *vma = vmf->vma;
pgprot_t pgprot = vma->vm_page_prot;
+
/*
* If we had pud_special, we could avoid all these restrictions,
* but we need to be consistent with PTEs and architectures that
@@ -889,7 +893,7 @@ vm_fault_t vmf_insert_pfn_pud(struct vm_

track_pfn_insert(vma, &pgprot, pfn);

- insert_pfn_pud(vma, addr, pud, pfn, pgprot, write);
+ insert_pfn_pud(vma, addr, vmf->pud, pfn, pgprot, write);
return VM_FAULT_NOPAGE;
}
EXPORT_SYMBOL_GPL(vmf_insert_pfn_pud);

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