The patch titled
Subject: mm: change vmf_anon_prepare() to __vmf_anon_prepare()
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-change-vmf_anon_prepare-to-__vmf_anon_prepare.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-change-vmf_anon_prepare-to-__vmf_anon_prepare.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: "Vishal Moola (Oracle)" <vishal.moola@xxxxxxxxx>
Subject: mm: change vmf_anon_prepare() to __vmf_anon_prepare()
Date: Sat, 14 Sep 2024 12:41:18 -0700
Some callers of vmf_anon_prepare() may not want us to release the per-VMA
lock ourselves. Rename vmf_anon_prepare() to __vmf_anon_prepare() and let
the callers drop the lock when desired.
Also, make vmf_anon_prepare() a wrapper that releases the per-VMA lock
itself for any callers that don't care.
This is in preparation to fix this bug reported by syzbot:
https://lore.kernel.org/linux-mm/00000000000067c20b06219fbc26@xxxxxxxxxx/
Link: https://lkml.kernel.org/r/20240914194243.245-1-vishal.moola@xxxxxxxxx
Fixes: 9acad7ba3e25 ("hugetlb: use vmf_anon_prepare() instead of anon_vma_prepare()")
Reported-by: syzbot+2dab93857ee95f2eeb08@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://lore.kernel.org/linux-mm/00000000000067c20b06219fbc26@xxxxxxxxxx/
Signed-off-by: Vishal Moola (Oracle) <vishal.moola@xxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/internal.h | 11 ++++++++++-
mm/memory.c | 8 +++-----
2 files changed, 13 insertions(+), 6 deletions(-)
--- a/mm/internal.h~mm-change-vmf_anon_prepare-to-__vmf_anon_prepare
+++ a/mm/internal.h
@@ -310,7 +310,16 @@ static inline void wake_throttle_isolate
wake_up(wqh);
}
-vm_fault_t vmf_anon_prepare(struct vm_fault *vmf);
+vm_fault_t __vmf_anon_prepare(struct vm_fault *vmf);
+static inline vm_fault_t vmf_anon_prepare(struct vm_fault *vmf)
+{
+ vm_fault_t ret = __vmf_anon_prepare(vmf);
+
+ if (unlikely(ret & VM_FAULT_RETRY))
+ vma_end_read(vmf->vma);
+ return ret;
+}
+
vm_fault_t do_swap_page(struct vm_fault *vmf);
void folio_rotate_reclaimable(struct folio *folio);
bool __folio_end_writeback(struct folio *folio);
--- a/mm/memory.c~mm-change-vmf_anon_prepare-to-__vmf_anon_prepare
+++ a/mm/memory.c
@@ -3259,7 +3259,7 @@ static inline vm_fault_t vmf_can_call_fa
}
/**
- * vmf_anon_prepare - Prepare to handle an anonymous fault.
+ * __vmf_anon_prepare - Prepare to handle an anonymous fault.
* @vmf: The vm_fault descriptor passed from the fault handler.
*
* When preparing to insert an anonymous page into a VMA from a
@@ -3273,7 +3273,7 @@ static inline vm_fault_t vmf_can_call_fa
* Return: 0 if fault handling can proceed. Any other value should be
* returned to the caller.
*/
-vm_fault_t vmf_anon_prepare(struct vm_fault *vmf)
+vm_fault_t __vmf_anon_prepare(struct vm_fault *vmf)
{
struct vm_area_struct *vma = vmf->vma;
vm_fault_t ret = 0;
@@ -3281,10 +3281,8 @@ vm_fault_t vmf_anon_prepare(struct vm_fa
if (likely(vma->anon_vma))
return 0;
if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
- if (!mmap_read_trylock(vma->vm_mm)) {
- vma_end_read(vma);
+ if (!mmap_read_trylock(vma->vm_mm))
return VM_FAULT_RETRY;
- }
}
if (__anon_vma_prepare(vma))
ret = VM_FAULT_OOM;
_
Patches currently in -mm which might be from vishal.moola@xxxxxxxxx are
mm-change-vmf_anon_prepare-to-__vmf_anon_prepare.patch
mm-hugetlbc-fix-uaf-of-vma-in-hugetlb-fault-pathway.patch
