diff options
| author | Konstantin Belousov <kib@FreeBSD.org> | 2025-11-21 08:34:51 +0000 |
|---|---|---|
| committer | Konstantin Belousov <kib@FreeBSD.org> | 2025-11-21 15:02:21 +0000 |
| commit | d8bfcacd12aba73188c44a157c707908e275825d (patch) | |
| tree | 6a824d29ad4e21b67b24a0140ec5050cd9e14f8b | |
| parent | b9fc7628dbb24b55cbb8791c83bd69f73cfadf23 (diff) | |
vm_fault: add a verifier that the PG_ZERO page is indeed zeroed
Compiled under INVARIANTS, activated by the same sysctl
debug.vm_check_pg_zero.
Reviewed by: markj
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Differential revision: https://reviews.freebsd.org/D53850
| -rw-r--r-- | sys/vm/vm_fault.c | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/sys/vm/vm_fault.c b/sys/vm/vm_fault.c index 2e150b368d71..3bf16778d987 100644 --- a/sys/vm/vm_fault.c +++ b/sys/vm/vm_fault.c @@ -85,6 +85,8 @@ #include <sys/refcount.h> #include <sys/resourcevar.h> #include <sys/rwlock.h> +#include <sys/sched.h> +#include <sys/sf_buf.h> #include <sys/signalvar.h> #include <sys/sysctl.h> #include <sys/sysent.h> @@ -1220,6 +1222,24 @@ vm_fault_zerofill(struct faultstate *fs) if ((fs->m->flags & PG_ZERO) == 0) { pmap_zero_page(fs->m); } else { +#ifdef INVARIANTS + if (vm_check_pg_zero) { + struct sf_buf *sf; + unsigned long *p; + int i; + + sched_pin(); + sf = sf_buf_alloc(fs->m, SFB_CPUPRIVATE); + p = (unsigned long *)sf_buf_kva(sf); + for (i = 0; i < PAGE_SIZE / sizeof(*p); i++, p++) { + KASSERT(*p == 0, + ("zerocheck failed page %p PG_ZERO %d %jx", + fs->m, i, (uintmax_t)*p)); + } + sf_buf_free(sf); + sched_unpin(); + } +#endif VM_CNT_INC(v_ozfod); } VM_CNT_INC(v_zfod); |