The patch titled
Subject: powerpc/mm: fix mmap_lock bad unlock
has been added to the -mm mm-unstable branch. Its filename is
powerc-mm-try-vma-lock-based-page-fault-handling-first-fix.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/powerc-mm-try-vma-lock-based-page-fault-handling-first-fix.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Laurent Dufour <ldufour@xxxxxxxxxxxxx>
Subject: powerpc/mm: fix mmap_lock bad unlock
Date: Mon, 6 Mar 2023 16:42:44 +0100
When page fault is tried holding the per VMA lock, bad_access_pkey() and
bad_access() should not be called because it is assuming the mmap_lock is
held. In the case a bad access is detected, fall back to the default
path, grabbing the mmap_lock to handle the fault and report the error.
Link: https://lkml.kernel.org/r/20230306154244.17560-1-ldufour@xxxxxxxxxxxxx
Fixes: 169db3bb4609 ("powerc/mm: try VMA lock-based page fault handling first")
Signed-off-by: Laurent Dufour <ldufour@xxxxxxxxxxxxx>
Reported-by: Sachin Sant <sachinp@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/linux-mm/842502FB-F99C-417C-9648-A37D0ECDC9CE@xxxxxxxxxxxxx
Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/arch/powerpc/mm/fault.c~powerc-mm-try-vma-lock-based-page-fault-handling-first-fix
+++ a/arch/powerpc/mm/fault.c
@@ -479,17 +479,13 @@ static int ___do_page_fault(struct pt_re
if (unlikely(access_pkey_error(is_write, is_exec,
(error_code & DSISR_KEYFAULT), vma))) {
- int rc = bad_access_pkey(regs, address, vma);
-
vma_end_read(vma);
- return rc;
+ goto lock_mmap;
}
if (unlikely(access_error(is_write, is_exec, vma))) {
- int rc = bad_access(regs, address);
-
vma_end_read(vma);
- return rc;
+ goto lock_mmap;
}
fault = handle_mm_fault(vma, address, flags | FAULT_FLAG_VMA_LOCK, regs);
_
Patches currently in -mm which might be from ldufour@xxxxxxxxxxxxx are
powerc-mm-try-vma-lock-based-page-fault-handling-first.patch
powerc-mm-try-vma-lock-based-page-fault-handling-first-fix.patch
