linux-kernel - [PATCH v2] mm/vmalloc: Separate put pages and flush VM flags

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Message-Id: <20210122233706.9304-1-rick.p.edgecombe@intel.com>
Date:   Fri, 22 Jan 2021 15:37:06 -0800
From:   Rick Edgecombe <rick.p.edgecombe@...el.com>
To:     akpm@...ux-foundation.org
Cc:     hch@....de, dja@...ens.net, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, willy@...radead.org,
        linmiaohe@...wei.com, Rick Edgecombe <rick.p.edgecombe@...el.com>
Subject: [PATCH v2] mm/vmalloc: Separate put pages and flush VM flags

When VM_MAP_PUT_PAGES was added, it was defined with the same value as
VM_FLUSH_RESET_PERMS. This doesn't seem like it will cause any big
functional problems other than some excess flushing for VM_MAP_PUT_PAGES
allocations.

Redefine VM_MAP_PUT_PAGES to have its own value. Also, rearrange things
so flags are less likely to be missed in the future.

Fixes: b944afc9d64d ("mm: add a VM_MAP_PUT_PAGES flag for vmap")
Suggested-by: Matthew Wilcox <willy@...radead.org>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
---

[v2]
Changed comment format like suggested by Matthew and listed him as Suggested-by.
Dropped Reviewed-bys because all of the comment changes are different.

 include/linux/vmalloc.h | 9 ++-------
 1 file changed, 2 insertions(+), 7 deletions(-)

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 80c0181c411d..cedcda6593f6 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -24,7 +24,8 @@ struct notifier_block;		/* in notifier.h */
 #define VM_UNINITIALIZED	0x00000020	/* vm_struct is not fully initialized */
 #define VM_NO_GUARD		0x00000040      /* don't add guard page */
 #define VM_KASAN		0x00000080      /* has allocated kasan shadow memory */
-#define VM_MAP_PUT_PAGES	0x00000100	/* put pages and free array in vfree */
+#define VM_FLUSH_RESET_PERMS	0x00000100	/* reset direct map and flush TLB on unmap, can't be freed in atomic context */
+#define VM_MAP_PUT_PAGES	0x00000200	/* put pages and free array in vfree */
 
 /*
  * VM_KASAN is used slighly differently depending on CONFIG_KASAN_VMALLOC.
@@ -37,12 +38,6 @@ struct notifier_block;		/* in notifier.h */
  * determine which allocations need the module shadow freed.
  */
 
-/*
- * Memory with VM_FLUSH_RESET_PERMS cannot be freed in an interrupt or with
- * vfree_atomic().
- */
-#define VM_FLUSH_RESET_PERMS	0x00000100      /* Reset direct map and flush TLB on unmap */
-
 /* bits [20..32] reserved for arch specific ioremap internals */
 
 /*
-- 
2.20.1