From 6ada4e8a0ae901f0012015c8d277d80aad7d8f37 Mon Sep 17 00:00:00 2001 From: Konstantin Belousov Date: Wed, 8 May 2024 16:58:52 +0300 Subject: [PATCH] swap-like pagers: assert that writemapping decrease does not pass zero Reviewed by: markj Tested by: pho Sponsored by: The FreeBSD Foundation MFC after: 1 week Differential revision: https://reviews.freebsd.org/D45119 --- sys/fs/tmpfs/tmpfs_subr.c | 3 +++ sys/vm/swap_pager.c | 4 ++++ 2 files changed, 7 insertions(+) diff --git a/sys/fs/tmpfs/tmpfs_subr.c b/sys/fs/tmpfs/tmpfs_subr.c index 84ce323441c..4ddf2b4ba5f 100644 --- a/sys/fs/tmpfs/tmpfs_subr.c +++ b/sys/fs/tmpfs/tmpfs_subr.c @@ -183,6 +183,9 @@ tmpfs_pager_release_writecount(vm_object_t object, vm_offset_t start, KASSERT((object->flags & OBJ_ANON) == 0, ("%s: object %p with OBJ_ANON", __func__, object)); old = object->un_pager.swp.writemappings; + KASSERT(old >= (vm_ooffset_t)end - start, + ("tmpfs obj %p writecount %jx dec %jx", object, (uintmax_t)old, + (uintmax_t)((vm_ooffset_t)end - start))); object->un_pager.swp.writemappings -= (vm_ooffset_t)end - start; new = object->un_pager.swp.writemappings; tmpfs_pager_writecount_recalc(object, old, new); diff --git a/sys/vm/swap_pager.c b/sys/vm/swap_pager.c index ee236c7f398..a07a3848149 100644 --- a/sys/vm/swap_pager.c +++ b/sys/vm/swap_pager.c @@ -3158,6 +3158,10 @@ swap_pager_release_writecount(vm_object_t object, vm_offset_t start, VM_OBJECT_WLOCK(object); KASSERT((object->flags & OBJ_ANON) == 0, ("Splittable object with writecount")); + KASSERT(object->un_pager.swp.writemappings >= (vm_ooffset_t)end - start, + ("swap obj %p writecount %jx dec %jx", object, + (uintmax_t)object->un_pager.swp.writemappings, + (uintmax_t)((vm_ooffset_t)end - start))); object->un_pager.swp.writemappings -= (vm_ooffset_t)end - start; VM_OBJECT_WUNLOCK(object); }