fs/proc/task_mmu: remove conversion of seq_file position to unsigned

Back in 2.6 era, last_addr used to be stored in seq_file->version
variable, which was unsigned long.  As a result, sentinels to represent
gate vma and end of all vmas used unsigned values.  In more recent kernels
we don't used seq_file->version anymore and therefore conversion from
loff_t into unsigned type is not needed.  Similarly, sentinel values don't
need to be unsigned.  Remove type conversion for set_file position and
change sentinel values to signed.  While at it, change the hardcoded
sentinel values with named definitions for better documentation.

Link: https://lkml.kernel.org/r/20250719182854.3166724-6-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Jann Horn <jannh@google.com>
Cc: Jeongjun Park <aha310510@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: T.J. Mercier <tjmercier@google.com>
Cc: Ye Bin <yebin10@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 10 insertions, 7 deletions

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 751479eb128f..90237df1ed33 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -29,6 +29,9 @@
 #include <asm/tlbflush.h>
 #include "internal.h"
 
+#define SENTINEL_VMA_END	-1
+#define SENTINEL_VMA_GATE	-2
+
 #define SEQ_PUT_DEC(str, val) \
 		seq_put_decimal_ull_width(m, str, (val) << (PAGE_SHIFT-10), 8)
 void task_mem(struct seq_file *m, struct mm_struct *mm)
@@ -135,7 +138,7 @@ static struct vm_area_struct *proc_get_vma(struct proc_maps_private *priv,
 	if (vma) {
 		*ppos = vma->vm_start;
 	} else {
-		*ppos = -2UL;
+		*ppos = SENTINEL_VMA_GATE;
 		vma = get_gate_vma(priv->mm);
 	}
 
@@ -145,11 +148,11 @@ static struct vm_area_struct *proc_get_vma(struct proc_maps_private *priv,
 static void *m_start(struct seq_file *m, loff_t *ppos)
 {
 	struct proc_maps_private *priv = m->private;
-	unsigned long last_addr = *ppos;
+	loff_t last_addr = *ppos;
 	struct mm_struct *mm;
 
 	/* See m_next(). Zero at the start or after lseek. */
-	if (last_addr == -1UL)
+	if (last_addr == SENTINEL_VMA_END)
 		return NULL;
 
 	priv->task = get_proc_task(priv->inode);
@@ -170,9 +173,9 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
 		return ERR_PTR(-EINTR);
 	}
 
-	vma_iter_init(&priv->iter, mm, last_addr);
+	vma_iter_init(&priv->iter, mm, (unsigned long)last_addr);
 	hold_task_mempolicy(priv);
-	if (last_addr == -2UL)
+	if (last_addr == SENTINEL_VMA_GATE)
 		return get_gate_vma(mm);
 
 	return proc_get_vma(priv, ppos);
@@ -180,8 +183,8 @@ static void *m_start(struct seq_file *m, loff_t *ppos)
 
 static void *m_next(struct seq_file *m, void *v, loff_t *ppos)
 {
-	if (*ppos == -2UL) {
-		*ppos = -1UL;
+	if (*ppos == SENTINEL_VMA_GATE) {
+		*ppos = SENTINEL_VMA_END;
 		return NULL;
 	}
 	return proc_get_vma(m->private, ppos);