> From: Li RongQing <[email protected]>
>
> In commit 1728ab54b4be ("x86/sgx: Add a page reclaimer") (v5.11),
> list_for_each_entry_rcu() was used to traverse the enclave's mm_list.
> However, this is incorrect because the list is protected by a Sleepable RCU
> (SRCU)
> lock (encl->srcu).
>
> Since commit 28875945ba98 ("rcu: Add support for consolidated-RCU reader
> checking") (v5.4), RCU lockdep checking has become stricter. When
> CONFIG_PROVE_RCU is enabled, using the standard list_for_each_entry_rcu()
> while only holding an SRCU lock triggers "suspicious RCU usage" false positive
> warnings, as it does not recognize SRCU read-side critical sections.
>
> Fix this by switching to list_for_each_entry_srcu(), which was introduced
> specifically for this purpose in commit ae2212a7216b
> ("rculist: Introduce list/hlist_for_each_entry_srcu() macros") (v5.10).
> This correctly associates the traversal with the SRCU lock and eliminates the
> lockdep warnings.
>
Ping
[Li,Rongqing]
> Fixes: 1728ab54b4be ("x86/sgx: Add a page reclaimer")
> Signed-off-by: Li RongQing <[email protected]>
> Acked-by: Kai Huang <[email protected]>
> ---
> Diff with v1: rewrite changelog
>
> arch/x86/kernel/cpu/sgx/encl.c | 12 ++++++++----
> arch/x86/kernel/cpu/sgx/main.c | 3 ++-
> 2 files changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/kernel/cpu/sgx/encl.c b/arch/x86/kernel/cpu/sgx/encl.c
> index ac60ebd..91362d7 100644
> --- a/arch/x86/kernel/cpu/sgx/encl.c
> +++ b/arch/x86/kernel/cpu/sgx/encl.c
> @@ -822,7 +822,8 @@ static struct sgx_encl_mm *sgx_encl_find_mm(struct
> sgx_encl *encl,
>
> idx = srcu_read_lock(&encl->srcu);
>
> - list_for_each_entry_rcu(tmp, &encl->mm_list, list) {
> + list_for_each_entry_srcu(tmp, &encl->mm_list, list,
> + srcu_read_lock_held(&encl->srcu)) {
> if (tmp->mm == mm) {
> encl_mm = tmp;
> break;
> @@ -933,7 +934,8 @@ const cpumask_t *sgx_encl_cpumask(struct sgx_encl
> *encl)
>
> idx = srcu_read_lock(&encl->srcu);
>
> - list_for_each_entry_rcu(encl_mm, &encl->mm_list, list) {
> + list_for_each_entry_srcu(encl_mm, &encl->mm_list, list,
> + srcu_read_lock_held(&encl->srcu)) {
> if (!mmget_not_zero(encl_mm->mm))
> continue;
>
> @@ -1018,7 +1020,8 @@ static struct mem_cgroup
> *sgx_encl_get_mem_cgroup(struct sgx_encl *encl)
> */
> idx = srcu_read_lock(&encl->srcu);
>
> - list_for_each_entry_rcu(encl_mm, &encl->mm_list, list) {
> + list_for_each_entry_srcu(encl_mm, &encl->mm_list, list,
> + srcu_read_lock_held(&encl->srcu)) {
> if (!mmget_not_zero(encl_mm->mm))
> continue;
>
> @@ -1212,7 +1215,8 @@ void sgx_zap_enclave_ptes(struct sgx_encl *encl,
> unsigned long addr)
>
> idx = srcu_read_lock(&encl->srcu);
>
> - list_for_each_entry_rcu(encl_mm, &encl->mm_list, list) {
> + list_for_each_entry_srcu(encl_mm, &encl->mm_list, list,
> + srcu_read_lock_held(&encl->srcu)) {
> if (!mmget_not_zero(encl_mm->mm))
> continue;
>
> diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
> index 38b7fd2..581e0c4 100644
> --- a/arch/x86/kernel/cpu/sgx/main.c
> +++ b/arch/x86/kernel/cpu/sgx/main.c
> @@ -120,7 +120,8 @@ static bool sgx_reclaimer_age(struct sgx_epc_page
> *epc_page)
>
> idx = srcu_read_lock(&encl->srcu);
>
> - list_for_each_entry_rcu(encl_mm, &encl->mm_list, list) {
> + list_for_each_entry_srcu(encl_mm, &encl->mm_list, list,
> + srcu_read_lock_held(&encl->srcu)) {
> if (!mmget_not_zero(encl_mm->mm))
> continue;
>
> --
> 2.9.4
