From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: + mm-mmu_notifier-silence-prove_rcu_list-warnings.patch added to -mm tree Date: Tue, 17 Mar 2020 20:12:52 -0700 Message-ID: <20200318031252.ukqP7B6OZ%akpm@linux-foundation.org> References: <20200305222751.6d781a3f2802d79510941e4e@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:57696 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726229AbgCRDMz (ORCPT ); Tue, 17 Mar 2020 23:12:55 -0400 In-Reply-To: <20200305222751.6d781a3f2802d79510941e4e@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: cai@lca.pw, jgg@ziepe.ca, mm-commits@vger.kernel.org, paulmck@kernel.org The patch titled Subject: mm/mmu_notifier: silence PROVE_RCU_LIST warnings has been added to the -mm tree. Its filename is mm-mmu_notifier-silence-prove_rcu_list-warnings.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-mmu_notifier-silence-prove_rcu_list-warnings.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-mmu_notifier-silence-prove_rcu_list-warnings.patch 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 and is updated there every 3-4 working days ------------------------------------------------------ From: Qian Cai Subject: mm/mmu_notifier: silence PROVE_RCU_LIST warnings It is safe to traverse mm->notifier_subscriptions->list either under SRCU read lock or mm->notifier_subscriptions->lock using hlist_for_each_entry_rcu(). Silence the PROVE_RCU_LIST false positives, for example, WARNING: suspicious RCU usage ----------------------------- mm/mmu_notifier.c:484 RCU-list traversed in non-reader section!! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 3 locks held by libvirtd/802: #0: ffff9321e3f58148 (&mm->mmap_sem#2){++++}, at: do_mprotect_pkey+0xe1/0x3e0 #1: ffffffff91ae6160 (mmu_notifier_invalidate_range_start){+.+.}, at: change_p4d_range+0x5fa/0x800 #2: ffffffff91ae6e08 (srcu){....}, at: __mmu_notifier_invalidate_range_start+0x178/0x460 stack backtrace: CPU: 7 PID: 802 Comm: libvirtd Tainted: G I 5.6.0-rc6-next-20200317+ #2 Hardware name: HP ProLiant BL460c Gen8, BIOS I31 11/02/2014 Call Trace: dump_stack+0xa4/0xfe lockdep_rcu_suspicious+0xeb/0xf5 __mmu_notifier_invalidate_range_start+0x3ff/0x460 change_p4d_range+0x746/0x800 change_protection+0x1df/0x300 mprotect_fixup+0x245/0x3e0 do_mprotect_pkey+0x23b/0x3e0 __x64_sys_mprotect+0x51/0x70 do_syscall_64+0x91/0xae8 entry_SYSCALL_64_after_hwframe+0x49/0xb3 Link: http://lkml.kernel.org/r/20200317175640.2047-1-cai@lca.pw Signed-off-by: Qian Cai Reviewed-by: Paul E. McKenney Cc: Jason Gunthorpe Signed-off-by: Andrew Morton --- mm/mmu_notifier.c | 27 ++++++++++++++++++--------- 1 file changed, 18 insertions(+), 9 deletions(-) --- a/mm/mmu_notifier.c~mm-mmu_notifier-silence-prove_rcu_list-warnings +++ a/mm/mmu_notifier.c @@ -307,7 +307,8 @@ static void mn_hlist_release(struct mmu_ * ->release returns. */ id = srcu_read_lock(&srcu); - hlist_for_each_entry_rcu(subscription, &subscriptions->list, hlist) + hlist_for_each_entry_rcu(subscription, &subscriptions->list, hlist, + srcu_read_lock_held(&srcu)) /* * If ->release runs before mmu_notifier_unregister it must be * handled, as it's the only way for the driver to flush all @@ -370,7 +371,8 @@ int __mmu_notifier_clear_flush_young(str id = srcu_read_lock(&srcu); hlist_for_each_entry_rcu(subscription, - &mm->notifier_subscriptions->list, hlist) { + &mm->notifier_subscriptions->list, hlist, + srcu_read_lock_held(&srcu)) { if (subscription->ops->clear_flush_young) young |= subscription->ops->clear_flush_young( subscription, mm, start, end); @@ -389,7 +391,8 @@ int __mmu_notifier_clear_young(struct mm id = srcu_read_lock(&srcu); hlist_for_each_entry_rcu(subscription, - &mm->notifier_subscriptions->list, hlist) { + &mm->notifier_subscriptions->list, hlist, + srcu_read_lock_held(&srcu)) { if (subscription->ops->clear_young) young |= subscription->ops->clear_young(subscription, mm, start, end); @@ -407,7 +410,8 @@ int __mmu_notifier_test_young(struct mm_ id = srcu_read_lock(&srcu); hlist_for_each_entry_rcu(subscription, - &mm->notifier_subscriptions->list, hlist) { + &mm->notifier_subscriptions->list, hlist, + srcu_read_lock_held(&srcu)) { if (subscription->ops->test_young) { young = subscription->ops->test_young(subscription, mm, address); @@ -428,7 +432,8 @@ void __mmu_notifier_change_pte(struct mm id = srcu_read_lock(&srcu); hlist_for_each_entry_rcu(subscription, - &mm->notifier_subscriptions->list, hlist) { + &mm->notifier_subscriptions->list, hlist, + srcu_read_lock_held(&srcu)) { if (subscription->ops->change_pte) subscription->ops->change_pte(subscription, mm, address, pte); @@ -476,7 +481,8 @@ static int mn_hlist_invalidate_range_sta int id; id = srcu_read_lock(&srcu); - hlist_for_each_entry_rcu(subscription, &subscriptions->list, hlist) { + hlist_for_each_entry_rcu(subscription, &subscriptions->list, hlist, + srcu_read_lock_held(&srcu)) { const struct mmu_notifier_ops *ops = subscription->ops; if (ops->invalidate_range_start) { @@ -528,7 +534,8 @@ mn_hlist_invalidate_end(struct mmu_notif int id; id = srcu_read_lock(&srcu); - hlist_for_each_entry_rcu(subscription, &subscriptions->list, hlist) { + hlist_for_each_entry_rcu(subscription, &subscriptions->list, hlist, + srcu_read_lock_held(&srcu)) { /* * Call invalidate_range here too to avoid the need for the * subsystem of having to register an invalidate_range_end @@ -582,7 +589,8 @@ void __mmu_notifier_invalidate_range(str id = srcu_read_lock(&srcu); hlist_for_each_entry_rcu(subscription, - &mm->notifier_subscriptions->list, hlist) { + &mm->notifier_subscriptions->list, hlist, + srcu_read_lock_held(&srcu)) { if (subscription->ops->invalidate_range) subscription->ops->invalidate_range(subscription, mm, start, end); @@ -714,7 +722,8 @@ find_get_mmu_notifier(struct mm_struct * spin_lock(&mm->notifier_subscriptions->lock); hlist_for_each_entry_rcu(subscription, - &mm->notifier_subscriptions->list, hlist) { + &mm->notifier_subscriptions->list, hlist, + lockdep_is_held(&mm->notifier_subscriptions->lock)) { if (subscription->ops != ops) continue; _ Patches currently in -mm which might be from cai@lca.pw are page-flags-fix-a-crash-at-setpageerrorthp_swap.patch mm-kmemleak-silence-kcsan-splats-in-checksum.patch mm-disable-kcsan-for-kmemleak.patch mm-swapfile-fix-data-races-in-try_to_unuse.patch mm-mmu_notifier-silence-prove_rcu_list-warnings.patch kasan-detect-negative-size-in-memory-operation-function-fix.patch mm-vmscan-fix-data-races-at-kswapd_classzone_idx.patch percpu_counter-fix-a-data-race-at-vm_committed_as.patch mm-frontswap-mark-various-intentional-data-races.patch mm-page_io-mark-various-intentional-data-races.patch mm-page_io-mark-various-intentional-data-races-v2.patch mm-swap_state-mark-various-intentional-data-races.patch mm-swapfile-fix-and-annotate-various-data-races.patch mm-swapfile-fix-and-annotate-various-data-races-v2.patch mm-page_counter-fix-various-data-races-at-memsw.patch mm-memcontrol-fix-a-data-race-in-scan-count.patch mm-list_lru-fix-a-data-race-in-list_lru_count_one.patch mm-mempool-fix-a-data-race-in-mempool_free.patch mm-util-annotate-an-data-race-at-vm_committed_as.patch mm-rmap-annotate-a-data-race-at-tlb_flush_batched.patch mm-annotate-a-data-race-in-page_zonenum.patch mm-swap-annotate-data-races-for-lru_rotate_pvecs.patch