diff mbox series

[02/41] maple_tree: Detect dead nodes in mas_start()

Message ID	20230109205336.3665937-3-surenb@google.com (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org> Date: Mon, 9 Jan 2023 12:52:57 -0800 In-Reply-To: <20230109205336.3665937-1-surenb@google.com> Mime-Version: 1.0 References: <20230109205336.3665937-1-surenb@google.com> Message-ID: <20230109205336.3665937-3-surenb@google.com> Subject: [PATCH 02/41] maple_tree: Detect dead nodes in mas_start() From: Suren Baghdasaryan <surenb@google.com> To: akpm@linux-foundation.org Cc: michel@lespinasse.org, jglisse@google.com, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, mgorman@techsingularity.net, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, peterz@infradead.org, ldufour@linux.ibm.com, laurent.dufour@fr.ibm.com, paulmck@kernel.org, luto@kernel.org, songliubraving@fb.com, peterx@redhat.com, david@redhat.com, dhowells@redhat.com, hughd@google.com, bigeasy@linutronix.de, kent.overstreet@linux.dev, punit.agrawal@bytedance.com, lstoakes@gmail.com, peterjung1337@gmail.com, rientjes@google.com, axelrasmussen@google.com, joelaf@google.com, minchan@google.com, jannh@google.com, shakeelb@google.com, tatashin@google.com, edumazet@google.com, gthelen@google.com, gurua@google.com, arjunroy@google.com, soheil@google.com, hughlynch@google.com, leewalsh@google.com, posk@google.com, linux-mm@kvack.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org, kernel-team@android.com, surenb@google.com, Liam Howlett <Liam.Howlett@oracle.com> Precedence: list Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" <linux-arm-kernel-bounces@lists.infradead.org> Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org
Series	Per-VMA locks \| expand [00/41] Per-VMA locks [01/41] maple_tree: Be more cautious about dead nodes [02/41] maple_tree: Detect dead nodes in mas_start() [03/41] maple_tree: Fix freeing of nodes in rcu mode [04/41] maple_tree: remove extra smp_wmb() from mas_dead_leaves() [05/41] maple_tree: Fix write memory barrier of nodes once dead for RCU mode [06/41] maple_tree: Add smp_rmb() to dead node detection [07/41] mm: Enable maple tree RCU mode by default. [08/41] mm: introduce CONFIG_PER_VMA_LOCK [09/41] mm: rcu safe VMA freeing [10/41] mm: move mmap_lock assert function definitions [11/41] mm: export dump_mm() [12/41] mm: add per-VMA lock and helper functions to control it [13/41] mm: introduce vma->vm_flags modifier functions [14/41] mm: replace VM_LOCKED_CLEAR_MASK with VM_LOCKED_MASK [15/41] mm: replace vma->vm_flags direct modifications with modifier calls [16/41] mm: replace vma->vm_flags indirect modification in ksm_madvise [17/41] mm/mmap: move VMA locking before anon_vma_lock_write call [18/41] mm/khugepaged: write-lock VMA while collapsing a huge page [19/41] mm/mmap: write-lock VMAs before merging, splitting or expanding them [20/41] mm/mmap: write-lock VMAs in vma_adjust [21/41] mm/mmap: write-lock VMAs affected by VMA expansion [22/41] mm/mremap: write-lock VMA while remapping it to a new address range [23/41] mm: write-lock VMAs before removing them from VMA tree [24/41] mm: conditionally write-lock VMA in free_pgtables [25/41] mm/mmap: write-lock adjacent VMAs if they can grow into unmapped area [26/41] kernel/fork: assert no VMA readers during its destruction [27/41] mm/mmap: prevent pagefault handler from racing with mmu_notifier registration [28/41] mm: introduce lock_vma_under_rcu to be used from arch-specific code [29/41] mm: fall back to mmap_lock if vma->anon_vma is not yet set [30/41] mm: add FAULT_FLAG_VMA_LOCK flag [31/41] mm: prevent do_swap_page from handling page faults under VMA lock [32/41] mm: prevent userfaults to be handled under per-vma lock [33/41] mm: introduce per-VMA lock statistics [34/41] x86/mm: try VMA lock-based page fault handling first [35/41] arm64/mm: try VMA lock-based page fault handling first [36/41] powerc/mm: try VMA lock-based page fault handling first [37/41] mm: introduce mod_vm_flags_nolock [38/41] mm: avoid assertion in untrack_pfn [39/41] kernel/fork: throttle call_rcu() calls in vm_area_free [40/41] mm: separate vma->lock from vm_area_struct [41/41] mm: replace rw_semaphore with atomic_t in vma_lock

Commit Message

Suren Baghdasaryan Jan. 9, 2023, 8:52 p.m. UTC

From: Liam Howlett <Liam.Howlett@oracle.com>

When initially starting a search, the root node may already be in the
process of being replaced in RCU mode.  Detect and restart the walk if
this is the case.  This is necessary for RCU mode of the maple tree.

Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Signed-off-by: Liam Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
 lib/maple_tree.c | 4 ++++
 1 file changed, 4 insertions(+)

diff mbox series

Patch

diff --git a/lib/maple_tree.c b/lib/maple_tree.c
index ff9f04e0150d..a748938ad2e9 100644
--- a/lib/maple_tree.c
+++ b/lib/maple_tree.c
@@ -1359,11 +1359,15 @@  static inline struct maple_enode *mas_start(struct ma_state *mas)
 		mas->depth = 0;
 		mas->offset = 0;
 
+retry:
 		root = mas_root(mas);
 		/* Tree with nodes */
 		if (likely(xa_is_node(root))) {
 			mas->depth = 1;
 			mas->node = mte_safe_root(root);
+			if (mte_dead_node(mas->node))
+				goto retry;
+
 			return NULL;
 		}