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alpha: fix the local TLB invalidate in the UP flush_tlb_page()

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The uniprocessor flush_tlb_page() in asm/tlbflush.h has the same wrong
test as the SMP one: a targeted tbi() is only guaranteed to invalidate
the intended translations when the target mm's context is loaded, but
the gate is current->active_mm, which a lazily borrowed mm also
satisfies.

Test current->mm instead. The else branch it falls to already exists
here, so unlike the SMP side this is the whole fix.
arch/alpha/kernel/smp.c is not built with CONFIG_SMP=n, so this is how
the same defect reaches a uniprocessor, where the flusher kworker
necessarily shares the only CPU with the writer.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Cc: stable@vger.kernel.org
Reviewed-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Magnus Lindholm <linmag7@gmail.com>
Link: https://lore.kernel.org/r/20261010142533.974797-7-linmag7@gmail.com
Signed-off-by: Magnus Lindholm <linmag7@gmail.com>
This commit is contained in:
Magnus Lindholm 2026-10-10 16:24:32 +02:00
parent 32f4dd420d
commit c825bf802a
1 changed files with 2 additions and 1 deletions
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3
arch/alpha/include/asm/tlbflush.h
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@ -87,7 +87,8 @@ flush_tlb_page(struct vm_area_struct *vma, unsigned long addr)
{
struct mm_struct *mm = vma->vm_mm;
if (mm == current->active_mm)
/* A targeted tbi() needs a thread of MM to be current. */
if (mm == current->mm)
flush_tlb_current_page(mm, vma, addr);
else
flush_tlb_other(mm);