Mirrors
/
netbsd-src
mirror of https://github.com/NetBSD/src.git
1
0
Fork 0
Code Issues Projects Releases Wiki Activity

radixtree: allocate memory with KM_NOSLEEP to prevent pagedaemon hangs 

Revert the part of rev 1.32 (reapplying "Do away with separate pool_cache
for some kernel objects") that changed the memory allocation for radixtree
nodes from PR_NOWAIT to KM_SLEEP as part of changing from a pool to kmem.
uvm_pageinsert_tree() calls into the radixtree code while holding
the object's vmobjlock, but that same lock is taken by the pagedaemon
in the process of reclaiming pages, and if the pagedaemon happens to
choose the same object to reclaim from that uvm_pageinsert_tree()
is being called on, then these two threads will deadlock.
The previous code already handled memory allocation failures
in uvm_pageinsert_tree() so we can simply change it back to nosleep.

Fixes a hang reported by simonb@, and the fix was also tested by him.
pull/36/head
chs 2024-05-04 17:58:24 +00:00
parent f8e4b988b6
commit 779666e6a0
1 changed files with 6 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
common/lib/libc/gen/radixtree.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: radixtree.c,v 1.33 2023/09/23 19:17:38 ad Exp $ */
/* $NetBSD: radixtree.c,v 1.34 2024/05/04 17:58:24 chs Exp $ */
/*-
* Copyright (c)2011,2012,2013 YAMAMOTO Takashi,
@ -112,7 +112,7 @@
#include <sys/cdefs.h>
#if defined(_KERNEL) || defined(_STANDALONE)
__KERNEL_RCSID(0, "$NetBSD: radixtree.c,v 1.33 2023/09/23 19:17:38 ad Exp $");
__KERNEL_RCSID(0, "$NetBSD: radixtree.c,v 1.34 2024/05/04 17:58:24 chs Exp $");
#include <sys/param.h>
#include <sys/errno.h>
#include <sys/kmem.h>
@ -122,7 +122,7 @@ __KERNEL_RCSID(0, "$NetBSD: radixtree.c,v 1.33 2023/09/23 19:17:38 ad Exp $");
#include <lib/libsa/stand.h>
#endif /* defined(_STANDALONE) */
#else /* defined(_KERNEL) || defined(_STANDALONE) */
__RCSID("$NetBSD: radixtree.c,v 1.33 2023/09/23 19:17:38 ad Exp $");
__RCSID("$NetBSD: radixtree.c,v 1.34 2024/05/04 17:58:24 chs Exp $");
#include <assert.h>
#include <errno.h>
#include <stdbool.h>
@ -410,9 +410,10 @@ radix_tree_alloc_node(void)
#if defined(_KERNEL)
/*
* note that kmem_alloc can block.
* We must not block waiting for memory because this function
* can be called in contexts where waiting for memory is illegal.
*/
n = kmem_intr_alloc(sizeof(struct radix_tree_node), KM_SLEEP);
n = kmem_intr_alloc(sizeof(struct radix_tree_node), KM_NOSLEEP);
#elif defined(_STANDALONE)
n = alloc(sizeof(*n));
#else /* defined(_STANDALONE) */