Date: Sat, 14 Jan 2017 19:35:36 +0000 (UTC) From: "Jason A. Harmening" <jah@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r312191 - head/sys/i386/i386 Message-ID: <201701141935.v0EJZaew026285@repo.freebsd.org>
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Author: jah Date: Sat Jan 14 19:35:36 2017 New Revision: 312191 URL: https://svnweb.freebsd.org/changeset/base/312191 Log: Add comment explaining relative order of sched_unpin() and mtx_unlock(). Suggested by: alc MFC after: 1 week Modified: head/sys/i386/i386/pmap.c Modified: head/sys/i386/i386/pmap.c ============================================================================== --- head/sys/i386/i386/pmap.c Sat Jan 14 18:04:12 2017 (r312190) +++ head/sys/i386/i386/pmap.c Sat Jan 14 19:35:36 2017 (r312191) @@ -4216,6 +4216,12 @@ pmap_zero_page(vm_page_t m) invlcaddr(pc->pc_cmap_addr2); pagezero(pc->pc_cmap_addr2); *cmap_pte2 = 0; + + /* + * Unpin the thread before releasing the lock. Otherwise the thread + * could be rescheduled while still bound to the current CPU, only + * to unpin itself immediately upon resuming execution. + */ sched_unpin(); mtx_unlock(&pc->pc_cmap_lock); }
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