Re: [PATCH v2 1/4] mm: Add optional close() to struct vm_special_mapping
From: Andrew Morton <akpm@linux-foundation.org>
Date: 2024-09-02 20:49:55
Also in:
linux-mm, linux-s390, linux-um, lkml
Possibly related (same subject, not in this thread)
- 2024-09-03 · Re: [PATCH v2 1/4] mm: Add optional close() to struct vm_special_mapping · Sven Schnelle <svens@linux.ibm.com>
- 2024-08-21 · Re: [PATCH v2 1/4] mm: Add optional close() to struct vm_special_mapping · Andrew Morton <akpm@linux-foundation.org>
- 2024-08-20 · Re: [PATCH v2 1/4] mm: Add optional close() to struct vm_special_mapping · Linus Torvalds <torvalds@linux-foundation.org>
- 2024-08-20 · Re: [PATCH v2 1/4] mm: Add optional close() to struct vm_special_mapping · Rob Landley <hidden>
- 2024-08-20 · Re: [PATCH v2 1/4] mm: Add optional close() to struct vm_special_mapping · Linus Torvalds <torvalds@linux-foundation.org>
On Mon, 02 Sep 2024 21:06:48 +0200 Sven Schnelle [off-list ref] wrote:
quoted hunk ↗ jump to hunk
So uprobe_clear_state() in the beginning free's the memory area containing the vm_special_mapping data, but exit_mmap() uses this address later via vma->vm_private_data (which was set in _install_special_mapping(). The following change fixes this for me, but i'm not sure about any side effects:diff --git a/kernel/fork.c b/kernel/fork.c index df8e4575ff01..cfcabba36c93 100644 --- a/kernel/fork.c +++ b/kernel/fork.c@@ -1340,11 +1340,11 @@ static inline void __mmput(struct mm_struct *mm) { VM_BUG_ON(atomic_read(&mm->mm_users)); - uprobe_clear_state(mm); exit_aio(mm); ksm_exit(mm); khugepaged_exit(mm); /* must run before exit_mmap */ exit_mmap(mm); + uprobe_clear_state(mm); mm_put_huge_zero_folio(mm); set_mm_exe_file(mm, NULL); if (!list_empty(&mm->mmlist)) {
uprobe_clear_state() is a pretty simple low-level thing. Side-effects seem unlikely?