d/freebsd-dev
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

vmem: Revert r364744

Browse Source 
A pair of bugs are believed to have caused the hangs described in the
commit log message for r364744:

1. uma_reclaim() could trigger reclamation of the reserve of boundary
   tags used to avoid deadlock.  This was fixed by r366840.
2. The loop in vmem_xalloc() would in some cases try to allocate more
   boundary tags than the expected upper bound of BT_MAXALLOC.  The
   reserve is sized based on the value BT_MAXMALLOC, so this behaviour
   could deplete the reserve without guaranteeing a successful
   allocation, resulting in a hang.  This was fixed by r366838.

PR:		248008
Tested by:	rmacklem
This commit is contained in:
Mark Johnston 2020-12-01 16:06:31 +00:00
parent c3afd20f13
commit dad22308a1
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=368236
1 changed files with 1 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
sys/kern/subr_vmem.c
View File

@ -706,14 +706,10 @@ vmem_startup(void)
vmem_zone = uma_zcreate("vmem",
sizeof(struct vmem), NULL, NULL, NULL, NULL,
UMA_ALIGN_PTR, 0);
#ifdef UMA_MD_SMALL_ALLOC
vmem_bt_zone = uma_zcreate("vmem btag",
sizeof(struct vmem_btag), NULL, NULL, NULL, NULL,
UMA_ALIGN_PTR, UMA_ZONE_VM);
#else
vmem_bt_zone = uma_zcreate("vmem btag",
sizeof(struct vmem_btag), NULL, NULL, NULL, NULL,
UMA_ALIGN_PTR, UMA_ZONE_VM | UMA_ZONE_NOFREE);
#ifndef UMA_MD_SMALL_ALLOC
mtx_init(&vmem_bt_lock, "btag lock", NULL, MTX_DEF);
uma_prealloc(vmem_bt_zone, BT_MAXALLOC);
/*