Grab the mutex before iterating on the global list.

Prevent race reported some months ago.

ok mlarkin@, jsg@, kn@

diff --git a/sys/uvm/uvm_pager.c b/sys/uvm/uvm_pager.c
index ed10740..adb3632 100644 (file)
--- a/sys/uvm/uvm_pager.c
+++ b/sys/uvm/uvm_pager.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: uvm_pager.c,v 1.88 2022/08/15 03:21:04 jsg Exp $      */
+/*     $OpenBSD: uvm_pager.c,v 1.89 2022/08/19 05:53:19 mpi Exp $      */
 /*     $NetBSD: uvm_pager.c,v 1.36 2000/11/27 18:26:41 chs Exp $       */
 
 /*
@@ -209,6 +209,7 @@ uvm_pseg_release(vaddr_t segaddr)
        struct uvm_pseg *pseg;
        vaddr_t va = 0;
 
+       mtx_enter(&uvm_pseg_lck);
        for (pseg = &psegs[0]; pseg != &psegs[PSEG_NUMSEGS]; pseg++) {
                if (pseg->start <= segaddr &&
                    segaddr < pseg->start + MAX_PAGER_SEGS * MAXBSIZE)
@@ -222,7 +223,6 @@ uvm_pseg_release(vaddr_t segaddr)
        /* test for no remainder */
        KDASSERT(segaddr == pseg->start + id * MAXBSIZE);
 
-       mtx_enter(&uvm_pseg_lck);
 
        KASSERT(UVM_PSEG_INUSE(pseg, id));