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...

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@gmail.com 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@google.com/

Link: https://lkml.kernel.org/r/20240914194243.245-1-vishal.moola@gmail.com Fixes: 9acad7ba3e25 ("hugetlb: use vmf_anon_prepare() instead of anon_vma_prepare()") Reported-by: syzbot+2dab93857ee95f2eeb08@syzkaller.appspotmail.com Closes: https://lore.kernel.org/linux-mm/00000000000067c20b06219fbc26@google.com/ Signed-off-by: Vishal Moola (Oracle) vishal.moola@gmail.com Cc: Muchun Song muchun.song@linux.dev Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

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@gmail.com are

mm-change-vmf_anon_prepare-to-__vmf_anon_prepare.patch mm-hugetlbc-fix-uaf-of-vma-in-hugetlb-fault-pathway.patch