bug-hurd
[Top][All Lists]
Advanced

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[PATCH] vm_page.c: fix a deadlock when running with smp enabled


From: Etienne Brateau
Subject: [PATCH] vm_page.c: fix a deadlock when running with smp enabled
Date: Mon, 2 Dec 2024 19:27:17 +0100

the call vm_page_seg_pull_cache_page() return an vm_page (src) with his
object being locked, as we don’t unlock before doing the vm_page_insert,
it is still lock there, and so trying to relock it cause a deadlock.
Replace this lock by an assert.
This case was not seen as for non-smp locking is a no-op.
---
 vm/vm_page.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/vm/vm_page.c b/vm/vm_page.c
index 286fe62f..e329354f 100644
--- a/vm/vm_page.c
+++ b/vm/vm_page.c
@@ -1036,7 +1036,8 @@ vm_page_seg_balance_page(struct vm_page_seg *seg,
     simple_unlock(&seg->lock);
     simple_unlock(&vm_page_queue_free_lock);
 
-    vm_object_lock(object);
+    // object is already locked as vm_page_seg_alloc_from_buddy return it 
locked
+    assert(vm_object_lock_taken(src->object) != 0);
     vm_page_insert(dest, object, offset);
     vm_object_unlock(object);
 
-- 
2.47.0




reply via email to

[Prev in Thread] Current Thread [Next in Thread]