Date: Tue, 1 Dec 2020 16:06:31 +0000 (UTC) From: Mark Johnston <markj@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r368236 - head/sys/kern Message-ID: <202012011606.0B1G6V12069341@repo.freebsd.org>
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Author: markj Date: Tue Dec 1 16:06:31 2020 New Revision: 368236 URL: https://svnweb.freebsd.org/changeset/base/368236 Log: vmem: Revert r364744 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 Modified: head/sys/kern/subr_vmem.c Modified: head/sys/kern/subr_vmem.c ============================================================================== --- head/sys/kern/subr_vmem.c Tue Dec 1 16:02:52 2020 (r368235) +++ head/sys/kern/subr_vmem.c Tue Dec 1 16:06:31 2020 (r368236) @@ -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); /*
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