mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-09-22 04:31:58 +08:00
fs/proc/task_mmu: fix loss of young/dirty bits during pagemap scan
make_uffd_wp_pte() was previously doing:
pte = ptep_get(ptep);
ptep_modify_prot_start(ptep);
pte = pte_mkuffd_wp(pte);
ptep_modify_prot_commit(ptep, pte);
But if another thread accessed or dirtied the pte between the first 2
calls, this could lead to loss of that information. Since
ptep_modify_prot_start() gets and clears atomically, the following is the
correct pattern and prevents any possible race. Any access after the
first call would see an invalid pte and cause a fault:
pte = ptep_modify_prot_start(ptep);
pte = pte_mkuffd_wp(pte);
ptep_modify_prot_commit(ptep, pte);
Link: https://lkml.kernel.org/r/20240429114017.182570-1-ryan.roberts@arm.com
Fixes: 52526ca7fd
("fs/proc/task_mmu: implement IOCTL to get and optionally clear info about PTEs")
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
parent
ac0476e8ca
commit
c70dce4982
@ -1825,7 +1825,7 @@ static void make_uffd_wp_pte(struct vm_area_struct *vma,
|
||||
pte_t old_pte;
|
||||
|
||||
old_pte = ptep_modify_prot_start(vma, addr, pte);
|
||||
ptent = pte_mkuffd_wp(ptent);
|
||||
ptent = pte_mkuffd_wp(old_pte);
|
||||
ptep_modify_prot_commit(vma, addr, pte, old_pte, ptent);
|
||||
} else if (is_swap_pte(ptent)) {
|
||||
ptent = pte_swp_mkuffd_wp(ptent);
|
||||
|
Loading…
Reference in New Issue
Block a user