This is a note to let you know that I've just added the patch titled
powerpc/vas: Don't set uses_vas for kernel windows
to the 4.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
powerpc-vas-don-t-set-uses_vas-for-kernel-windows.patch
and it can be found in the queue-4.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b00b62898631b756c3e123542bbb0487aa343dd9 Mon Sep 17 00:00:00 2001
From: Nicholas Piggin <npiggin@xxxxxxxxx>
Date: Thu, 8 Feb 2018 19:18:38 +1000
Subject: powerpc/vas: Don't set uses_vas for kernel windows
From: Nicholas Piggin <npiggin@xxxxxxxxx>
commit b00b62898631b756c3e123542bbb0487aa343dd9 upstream.
cp_abort is only required for user windows, because kernel context
must not be preempted between a copy/paste pair.
Without this patch, the init task gets used_vas set when it runs the
nx842_powernv_init initcall, which opens windows for kernel usage.
used_vas is then never cleared anywhere, so it gets propagated into
all other tasks. It's a property of the address space, so it should
really be cleared when a new mm is created (or in dup_mmap if the
mmaps are marked as VM_DONTCOPY). For now we seem to have no such
driver, so leave that for another patch.
Fixes: 6c8e6bb2a52d ("powerpc/vas: Add support for user receive window")
Cc: stable@xxxxxxxxxxxxxxx # v4.15+
Signed-off-by: Nicholas Piggin <npiggin@xxxxxxxxx>
Reviewed-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/platforms/powernv/vas-window.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
--- a/arch/powerpc/platforms/powernv/vas-window.c
+++ b/arch/powerpc/platforms/powernv/vas-window.c
@@ -1063,16 +1063,16 @@ struct vas_window *vas_tx_win_open(int v
rc = PTR_ERR(txwin->paste_kaddr);
goto free_window;
}
+ } else {
+ /*
+ * A user mapping must ensure that context switch issues
+ * CP_ABORT for this thread.
+ */
+ rc = set_thread_uses_vas();
+ if (rc)
+ goto free_window;
}
- /*
- * Now that we have a send window, ensure context switch issues
- * CP_ABORT for this thread.
- */
- rc = -EINVAL;
- if (set_thread_uses_vas() < 0)
- goto free_window;
-
set_vinst_win(vinst, txwin);
return txwin;
Patches currently in stable-queue which might be from npiggin@xxxxxxxxx are
queue-4.15/powerpc-vas-don-t-set-uses_vas-for-kernel-windows.patch