linux-kernel - [RFC v1 1/4] exit: add arch mmput hook in exit

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Date:   Thu, 11 Nov 2021 10:50:05 +0100
From:   Claudio Imbrenda <imbrenda@...ux.ibm.com>
To:     linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc:     thuth@...hat.com, frankja@...ux.ibm.com, borntraeger@...ibm.com,
        Ulrich.Weigand@...ibm.com, heiko.carstens@...ibm.com,
        david@...hat.com, ultrachin@....com, akpm@...ux-foundation.org,
        vbabka@...e.cz, brookxu.cn@...il.com, xiaoggchen@...cent.com,
        linuszeng@...cent.com, yihuilu@...cent.com, mhocko@...e.com,
        daniel.m.jordan@...cle.com, axboe@...nel.dk, legion@...nel.org,
        peterz@...radead.org, aarcange@...hat.com, christian@...uner.io,
        ebiederm@...ssion.com, tglx@...utronix.de
Subject: [RFC v1 1/4] exit: add arch mmput hook in exit_mm

This simple patch adds a hook for the mmput in exit_mm. This allows
archs to perform the mmput in custom ways if desired (e.g.
asynchronously)

No functional change intended.

Signed-off-by: Claudio Imbrenda <imbrenda@...ux.ibm.com>
---
 include/asm-generic/mmu_context.h | 4 ++++
 kernel/exit.c                     | 2 +-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/asm-generic/mmu_context.h b/include/asm-generic/mmu_context.h
index 91727065bacb..900931a6a105 100644
--- a/include/asm-generic/mmu_context.h
+++ b/include/asm-generic/mmu_context.h
@@ -73,4 +73,8 @@ static inline void deactivate_mm(struct task_struct *tsk,
 }
 #endif
 
+#ifndef arch_exit_mm_mmput
+#define arch_exit_mm_mmput mmput
+#endif
+
 #endif /* __ASM_GENERIC_MMU_CONTEXT_H */
diff --git a/kernel/exit.c b/kernel/exit.c
index f702a6a63686..6eb1fdcc434e 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -504,7 +504,7 @@ static void exit_mm(void)
 	task_unlock(current);
 	mmap_read_unlock(mm);
 	mm_update_next_owner(mm);
-	mmput(mm);
+	arch_exit_mm_mmput(mm);
 	if (test_thread_flag(TIF_MEMDIE))
 		exit_oom_victim();
 }
-- 
2.31.1