[PATCH 09/12] mm/madvise: add MADV_COLLAPSE to process_madvise()

From: "Zach O'Keefe" <zokeefe@google.com>
To: Alex Shi <alex.shi@linux.alibaba.com>,
	David Hildenbrand <david@redhat.com>,
	 David Rientjes <rientjes@google.com>,
	Matthew Wilcox <willy@infradead.org>,
	 Michal Hocko <mhocko@suse.com>,
	Pasha Tatashin <pasha.tatashin@soleen.com>,
	 SeongJae Park <sj@kernel.org>, Song Liu <songliubraving@fb.com>,
	Vlastimil Babka <vbabka@suse.cz>,  Yang Shi <shy828301@gmail.com>,
	Zi Yan <ziy@nvidia.com>,
	linux-mm@kvack.org
Cc: Andrea Arcangeli <aarcange@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	 Arnd Bergmann <arnd@arndb.de>,
	Axel Rasmussen <axelrasmussen@google.com>,
	 Chris Kennelly <ckennelly@google.com>,
	Chris Zankel <chris@zankel.net>, Helge Deller <deller@gmx.de>,
	 Hugh Dickins <hughd@google.com>,
	Ivan Kokshaysky <ink@jurassic.park.msu.ru>,
	 "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
	Jens Axboe <axboe@kernel.dk>,
	 "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Matt Turner <mattst88@gmail.com>,
	 Max Filippov <jcmvbkbc@gmail.com>,
	Miaohe Lin <linmiaohe@huawei.com>,
	 Minchan Kim <minchan@kernel.org>,
	Patrick Xia <patrickx@google.com>,
	 Pavel Begunkov <asml.silence@gmail.com>,
	Peter Xu <peterx@redhat.com>,
	 Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
	"Zach O'Keefe" <zokeefe@google.com>
Subject: [PATCH 09/12] mm/madvise: add MADV_COLLAPSE to process_madvise()
Date: Sun, 10 Apr 2022 06:54:42 -0700	[thread overview]
Message-ID: <20220410135445.3897054-10-zokeefe@google.com> (raw)
In-Reply-To: <20220410135445.3897054-1-zokeefe@google.com>

Allow MADV_COLLAPSE behavior for process_madvise(2) if caller has
CAP_SYS_ADMIN or is requesting collapse of it's own memory.

Signed-off-by: Zach O'Keefe <zokeefe@google.com>
---
 mm/madvise.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index 7ad53e5311cf..a5c82fa7972b 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1165,13 +1165,15 @@ madvise_behavior_valid(int behavior)
 }
 
 static bool
-process_madvise_behavior_valid(int behavior)
+process_madvise_behavior_valid(int behavior, struct task_struct *task)
 {
 	switch (behavior) {
 	case MADV_COLD:
 	case MADV_PAGEOUT:
 	case MADV_WILLNEED:
 		return true;
+	case MADV_COLLAPSE:
+		return task == current || capable(CAP_SYS_ADMIN);
 	default:
 		return false;
 	}
@@ -1449,7 +1451,7 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec,
 		goto free_iov;
 	}
 
-	if (!process_madvise_behavior_valid(behavior)) {
+	if (!process_madvise_behavior_valid(behavior, task)) {
 		ret = -EINVAL;
 		goto release_task;
 	}
-- 
2.35.1.1178.g4f1659d476-goog


