git: vm: allow writes to user-wired COW mappings

[Aaron LI]

commit f6679b2697dd08e5d914b57127402922825ea89e
Author: David Bidner <david at crap.solutions>
Date:   Sat Oct 3 11:24:23 2026 +0200

    vm: allow writes to user-wired COW mappings
    
    A later write to a MAP_PRIVATE mapping that was mlock()ed currently gets
    KERN_PROTECTION_FAILURE from vm_map_lookup() because the entry is both
    MAP_ENTRY_USER_WIRED and MAP_ENTRY_COW.  The normal page-fault path does
    not retry with VM_PROT_OVERRIDE_WRITE, so the write never completes and the
    process receives SIGSEGV.
    
    Fix the bug by removing the obsolete check so the normal copy-on-write
    path runs.
    
    vm_map_user_wiring() already created the shadow object before wiring the
    entry, so a later COW is a normal copy into the process's own shadow.  The
    NEEDS_COPY block below still creates the shadow if it was not created at
    wiring time.
    
    Reviewed-by: dillon
    Bug: https://bugs.dragonflybsd.org/issues/3431

Summary of changes:
 sys/vm/vm_map.c | 8 --------
 1 file changed, 8 deletions(-)

http://gitweb.dragonflybsd.org/dragonfly.git/commitdiff/f6679b2697dd08e5d914b57127402922825ea89e


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