The patch titled
Subject: Revert "kmsan: unpoison @tlb in arch_tlb_gather_mmu()"
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
revert-kmsan-unpoison-tlb-in-arch_tlb_gather_mmu.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/revert-kmsan-unpoison-tlb-in-arch_tlb_gather_mmu.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Alexander Potapenko <glider@xxxxxxxxxx>
Subject: Revert "kmsan: unpoison @tlb in arch_tlb_gather_mmu()"
Date: Thu, 10 Nov 2022 12:35:41 +0100
This reverts commit ac801e7e252c5588325e3c983c7d4167fc68c024.
The patch in question was picked to -mm from the KMSAN v6 patch series
(https://lore.kernel.org/linux-mm/20220905122452.2258262-1-glider@xxxxxxxxxx/)
and sneaked into mainline despite its removal from the v7 series
(https://lore.kernel.org/linux-mm/20220915150417.722975-1-glider@xxxxxxxxxx/)
Currently KMSAN does not warn about origin chains hitting the maximum
depth, so keeping @tlb poisoned won't result in any inconveniences.
Link: https://lkml.kernel.org/r/20221110113541.1844156-1-glider@xxxxxxxxxx
Signed-off-by: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Eric Biggers <ebiggers@xxxxxxxxxx>
Cc: Marco Elver <elver@xxxxxxxxxx>
Cc: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mmu_gather.c | 10 ----------
1 file changed, 10 deletions(-)
--- a/mm/mmu_gather.c~revert-kmsan-unpoison-tlb-in-arch_tlb_gather_mmu
+++ a/mm/mmu_gather.c
@@ -1,7 +1,6 @@
#include <linux/gfp.h>
#include <linux/highmem.h>
#include <linux/kernel.h>
-#include <linux/kmsan-checks.h>
#include <linux/mmdebug.h>
#include <linux/mm_types.h>
#include <linux/mm_inline.h>
@@ -266,15 +265,6 @@ void tlb_flush_mmu(struct mmu_gather *tl
static void __tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
bool fullmm)
{
- /*
- * struct mmu_gather contains 7 1-bit fields packed into a 32-bit
- * unsigned int value. The remaining 25 bits remain uninitialized
- * and are never used, but KMSAN updates the origin for them in
- * zap_pXX_range() in mm/memory.c, thus creating very long origin
- * chains. This is technically correct, but consumes too much memory.
- * Unpoisoning the whole structure will prevent creating such chains.
- */
- kmsan_unpoison_memory(tlb, sizeof(*tlb));
tlb->mm = mm;
tlb->fullmm = fullmm;
_
Patches currently in -mm which might be from glider@xxxxxxxxxx are
revert-kmsan-unpoison-tlb-in-arch_tlb_gather_mmu.patch
