Re: [PATCH] mm/huge_memory: Fix vmf_insert_pfn_{pmd, pud}() crash, handle unaligned addresses

From: Jan Kara
Date: Thu May 09 2019 - 15:33:39 EST

On Thu 09-05-19 09:31:41, Dan Williams wrote:
> Starting with commit 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
>
> Cc: <stable@xxxxxxxxxxxxxxx>
> Fixes: c6f3c5ee40c1 ("mm/huge_memory.c: fix modifying of page protection by insert_pfn_pmd()")
> Reported-by: Piotr Balcer <piotr.balcer@xxxxxxxxx>
> Tested-by: Yan Ma <yan.ma@xxxxxxxxx>
> Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
> Cc: Chandan Rajendra <chandan@xxxxxxxxxxxxx>
> Cc: Jan Kara <jack@xxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
> Cc: Souptick Joarder <jrdr.linux@xxxxxxxxx>
> Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>

Looks good to me. You can add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

Honza

> ---
>
> 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(-)
>
> diff --git a/drivers/dax/device.c b/drivers/dax/device.c
> index e428468ab661..996d68ff992a 100644
> --- a/drivers/dax/device.c
> +++ b/drivers/dax/device.c
> @@ -184,8 +184,7 @@ static vm_fault_t __dev_dax_pmd_fault(struct dev_dax *dev_dax,
>
> *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(struct dev_dax *dev_dax,
>
> *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,
> diff --git a/fs/dax.c b/fs/dax.c
> index e5e54da1715f..83009875308c 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -1575,8 +1575,7 @@ static vm_fault_t dax_iomap_pmd_fault(struct vm_fault *vmf, pfn_t *pfnp,
> }
>
> 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 *vmf, pfn_t pfn, unsigned int order)
> 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;
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index 381e872bfde0..7cd5c150c21d 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -47,10 +47,8 @@ extern bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
> 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,
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 165ea46bf149..4310c6e9e5a3 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -793,11 +793,13 @@ static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
> 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_area_struct *vma, unsigned long addr,
>
> 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 @@ static void insert_pfn_pud(struct vm_area_struct *vma, unsigned long addr,
> 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_area_struct *vma, unsigned long addr,
>
> 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);
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR