linux-kernel - [PATCH 13/16] mm: bool user_shm_lock(loff

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Date:   Fri, 30 Jul 2021 01:03:15 -0700 (PDT)
From:   Hugh Dickins <hughd@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
cc:     Hugh Dickins <hughd@...gle.com>,
        Shakeel Butt <shakeelb@...gle.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Yang Shi <shy828301@...il.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Michal Hocko <mhocko@...e.com>,
        Rik van Riel <riel@...riel.com>,
        Christoph Hellwig <hch@...radead.org>,
        Matthew Wilcox <willy@...radead.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Alexey Gladkov <legion@...nel.org>,
        Chris Wilson <chris@...is-wilson.co.uk>,
        Matthew Auld <matthew.auld@...el.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-api@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH 13/16] mm: bool user_shm_lock(loff_t size, struct ucounts
 *)

user_shm_lock()'s size_t size was big enough for SysV SHM locking, but
not quite big enough for O_LARGEFILE on 32-bit: change to loff_t size.
And while changing the prototype, let's use bool rather than int here.

Signed-off-by: Hugh Dickins <hughd@...gle.com>
---
 include/linux/mm.h |  4 ++--
 mm/mlock.c         | 14 +++++++-------
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7ca22e6e694a..f1be2221512b 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1713,8 +1713,8 @@ extern bool can_do_mlock(void);
 #else
 static inline bool can_do_mlock(void) { return false; }
 #endif
-extern int user_shm_lock(size_t, struct ucounts *);
-extern void user_shm_unlock(size_t, struct ucounts *);
+extern bool user_shm_lock(loff_t size, struct ucounts *ucounts);
+extern void user_shm_unlock(loff_t size, struct ucounts *ucounts);
 
 /*
  * Parameter block passed down to zap_pte_range in exceptional cases.
diff --git a/mm/mlock.c b/mm/mlock.c
index 16d2ee160d43..7df88fce0fc9 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -813,21 +813,21 @@ SYSCALL_DEFINE0(munlockall)
 }
 
 /*
- * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB
- * shm segments) get accounted against the user_struct instead.
+ * Objects with different lifetime than processes (SHM_LOCK and SHM_HUGETLB shm
+ * segments and F_MEM_LOCK tmpfs) get accounted to the user_namespace instead.
  */
 static DEFINE_SPINLOCK(shmlock_user_lock);
 
-int user_shm_lock(size_t size, struct ucounts *ucounts)
+bool user_shm_lock(loff_t size, struct ucounts *ucounts)
 {
 	unsigned long lock_limit, locked;
 	long memlock;
-	int allowed = 0;
+	bool allowed = false;
 
 	locked = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
 	lock_limit = rlimit(RLIMIT_MEMLOCK);
 	if (lock_limit == RLIM_INFINITY)
-		allowed = 1;
+		allowed = true;
 	lock_limit >>= PAGE_SHIFT;
 	spin_lock(&shmlock_user_lock);
 	memlock = inc_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked);
@@ -840,13 +840,13 @@ int user_shm_lock(size_t size, struct ucounts *ucounts)
 		dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, locked);
 		goto out;
 	}
-	allowed = 1;
+	allowed = true;
 out:
 	spin_unlock(&shmlock_user_lock);
 	return allowed;
 }
 
-void user_shm_unlock(size_t size, struct ucounts *ucounts)
+void user_shm_unlock(loff_t size, struct ucounts *ucounts)
 {
 	spin_lock(&shmlock_user_lock);
 	dec_rlimit_ucounts(ucounts, UCOUNT_RLIMIT_MEMLOCK, (size + PAGE_SIZE - 1) >> PAGE_SHIFT);
-- 
2.26.2