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um: Fix potential race condition in TLB sync

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During the TLB sync, we need to traverse and modify the page table,
so we should hold the page table lock. Since full SMP support for
threads within the same process is still missing, let's disable the
split page table lock for simplicity.

Fixes: 1e4ee5135d ("um: Add initial SMP support")
Signed-off-by: Tiwei Bie <tiwei.btw@antgroup.com>
Link: https://patch.msgid.link/20260302235224.1915380-2-tiwei.btw@antgroup.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Tiwei Bie 2026-03-03 07:52:23 +08:00 committed by Johannes Berg
parent 1ccc861dbb
commit 102331b66b
2 changed files with 2 additions and 0 deletions
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1
arch/um/kernel/tlb.c
View File

@ -165,6 +165,7 @@ int um_tlb_sync(struct mm_struct *mm)
unsigned long addr, next;
int ret = 0;
guard(spinlock_irqsave)(&mm->page_table_lock);
guard(spinlock_irqsave)(&mm->context.sync_tlb_lock);
if (mm->context.sync_tlb_range_to == 0)

1
mm/Kconfig
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@ -572,6 +572,7 @@ config SPLIT_PTE_PTLOCKS
depends on !ARM || CPU_CACHE_VIPT
depends on !PARISC || PA20
depends on !SPARC32
depends on !UML
config ARCH_ENABLE_SPLIT_PMD_PTLOCK
bool