linux-kernel - [PATCH v1 2/2] mm/madvise: add MADV_TRY_COLLAPSE to process

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Message-Id: <20240117050217.43610-2-ioworker0@gmail.com>
Date: Wed, 17 Jan 2024 13:02:17 +0800
From: Lance Yang <ioworker0@...il.com>
To: akpm@...ux-foundation.org
Cc: zokeefe@...gle.com,
	songmuchun@...edance.com,
	linux-kernel@...r.kernel.org,
	Lance Yang <ioworker0@...il.com>
Subject: [PATCH v1 2/2] mm/madvise: add MADV_TRY_COLLAPSE to process_madvise()

Allow MADV_TRY_COLLAPSE behavior for process_madvise(2) if the caller has
CAP_SYS_ADMIN or is requesting the collapse of its own memory.

The semantics of MADV_TRY_COLLAPSE are similar to MADV_COLLAPSE, but it
avoids direct reclaim and/or compaction, quickly failing on allocation errors.

This change enables a more flexible and efficient usage of memory collapse
operations, providing additional control to userspace applications for
system-wide THP optimization.

Signed-off-by: Lance Yang <ioworker0@...il.com>
---
 mm/madvise.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/madvise.c b/mm/madvise.c
index 5a359bcd286c..1f1bbaf2ffa1 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1205,6 +1205,7 @@ static bool process_madvise_behavior_valid(int behavior)
 	case MADV_PAGEOUT:
 	case MADV_WILLNEED:
 	case MADV_COLLAPSE:
+	case MADV_TRY_COLLAPSE:
 		return true;
 	default:
 		return false;
-- 
2.33.1