Re: 答复: [PATCH][v2] x86/sgx: Use list_for_each_entry_srcu() for mm_list traversal

[Jarkko Sakkinen]

On Tue, Apr 14, 2026 at 07:47:54AM +0000, Li,Rongqing(ACG CCN) wrote:
> 
> 
> > From: Li RongQing <lirongqing@xxxxxxxxx>
> > 
> > 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.
> > 
> > Fixes: 1728ab54b4be ("x86/sgx: Add a page reclaimer")
> > Signed-off-by: Li RongQing <lirongqing@xxxxxxxxx>
> > Acked-by: Kai Huang <kai.huang@xxxxxxxxx>
> > ---
> 
> Ping
> 
> thanks
> 
> [Li,Rongqing] 
> 
> 
> 
> > 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
> 


Reviewed-by: Jarkko Sakkinen <jarkko@xxxxxxxxxx>

BR, Jarkko