The patch titled
Subject: mm/mmap: prevent pagefault handler from racing with mmu_notifier registration
has been added to the -mm mm-unstable branch. Its filename is
mm-mmap-prevent-pagefault-handler-from-racing-with-mmu_notifier-registration.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mmap-prevent-pagefault-handler-from-racing-with-mmu_notifier-registration.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Subject: mm/mmap: prevent pagefault handler from racing with mmu_notifier registration
Date: Mon, 27 Feb 2023 09:36:20 -0800
Page fault handlers might need to fire MMU notifications while a new
notifier is being registered. Modify mm_take_all_locks to write-lock all
VMAs and prevent this race with page fault handlers that would hold VMA
locks. VMAs are locked before i_mmap_rwsem and anon_vma to keep the same
locking order as in page fault handlers.
Link: https://lkml.kernel.org/r/20230227173632.3292573-22-surenb@xxxxxxxxxx
Signed-off-by: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/mm/mmap.c~mm-mmap-prevent-pagefault-handler-from-racing-with-mmu_notifier-registration
+++ a/mm/mmap.c
@@ -3486,6 +3486,7 @@ static void vm_lock_mapping(struct mm_st
* of mm/rmap.c:
* - all hugetlbfs_i_mmap_rwsem_key locks (aka mapping->i_mmap_rwsem for
* hugetlb mapping);
+ * - all vmas marked locked
* - all i_mmap_rwsem locks;
* - all anon_vma->rwseml
*
@@ -3511,6 +3512,13 @@ int mm_take_all_locks(struct mm_struct *
mas_for_each(&mas, vma, ULONG_MAX) {
if (signal_pending(current))
goto out_unlock;
+ vma_start_write(vma);
+ }
+
+ mas_set(&mas, 0);
+ mas_for_each(&mas, vma, ULONG_MAX) {
+ if (signal_pending(current))
+ goto out_unlock;
if (vma->vm_file && vma->vm_file->f_mapping &&
is_vm_hugetlb_page(vma))
vm_lock_mapping(mm, vma->vm_file->f_mapping);
@@ -3597,6 +3605,7 @@ void mm_drop_all_locks(struct mm_struct
if (vma->vm_file && vma->vm_file->f_mapping)
vm_unlock_mapping(vma->vm_file->f_mapping);
}
+ vma_end_write_all(mm);
mutex_unlock(&mm_all_locks_mutex);
}
_
Patches currently in -mm which might be from surenb@xxxxxxxxxx are
mm-introduce-config_per_vma_lock.patch
mm-move-mmap_lock-assert-function-definitions.patch
mm-add-per-vma-lock-and-helper-functions-to-control-it.patch
mm-mark-vma-as-being-written-when-changing-vm_flags.patch
mm-mmap-move-vma_prepare-before-vma_adjust_trans_huge.patch
mm-khugepaged-write-lock-vma-while-collapsing-a-huge-page.patch
mm-mmap-write-lock-vmas-in-vma_prepare-before-modifying-them.patch
mm-mremap-write-lock-vma-while-remapping-it-to-a-new-address-range.patch
mm-write-lock-vmas-before-removing-them-from-vma-tree.patch
mm-conditionally-write-lock-vma-in-free_pgtables.patch
kernel-fork-assert-no-vma-readers-during-its-destruction.patch
mm-mmap-prevent-pagefault-handler-from-racing-with-mmu_notifier-registration.patch
mm-introduce-vma-detached-flag.patch
mm-introduce-lock_vma_under_rcu-to-be-used-from-arch-specific-code.patch
mm-fall-back-to-mmap_lock-if-vma-anon_vma-is-not-yet-set.patch
mm-add-fault_flag_vma_lock-flag.patch
mm-prevent-do_swap_page-from-handling-page-faults-under-vma-lock.patch
mm-prevent-userfaults-to-be-handled-under-per-vma-lock.patch
mm-introduce-per-vma-lock-statistics.patch
x86-mm-try-vma-lock-based-page-fault-handling-first.patch
arm64-mm-try-vma-lock-based-page-fault-handling-first.patch
mm-mmap-free-vm_area_struct-without-call_rcu-in-exit_mmap.patch
mm-separate-vma-lock-from-vm_area_struct.patch
per-vma-locks.patch
