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Message-ID: <20250731220024.702621-2-surenb@google.com>
Date: Thu, 31 Jul 2025 15:00:22 -0700
From: Suren Baghdasaryan <surenb@...gle.com>
To: akpm@...ux-foundation.org
Cc: Liam.Howlett@...cle.com, lorenzo.stoakes@...cle.com, david@...hat.com,
vbabka@...e.cz, peterx@...hat.com, jannh@...gle.com, hannes@...xchg.org,
mhocko@...nel.org, paulmck@...nel.org, shuah@...nel.org, adobriyan@...il.com,
brauner@...nel.org, josef@...icpanda.com, yebin10@...wei.com,
linux@...ssschuh.net, willy@...radead.org, osalvador@...e.de,
andrii@...nel.org, ryan.roberts@....com, christophe.leroy@...roup.eu,
tjmercier@...gle.com, kaleshsingh@...gle.com, aha310510@...il.com,
linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-mm@...ck.org, linux-kselftest@...r.kernel.org, surenb@...gle.com
Subject: [PATCH 1/3] selftests/proc: test PROCMAP_QUERY ioctl while vma is
concurrently modified
Extend /proc/pid/maps tearing tests to verify PROCMAP_QUERY ioctl operation
correctness while the vma is being concurrently modified.
Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
---
tools/testing/selftests/proc/proc-maps-race.c | 65 +++++++++++++++++++
1 file changed, 65 insertions(+)
diff --git a/tools/testing/selftests/proc/proc-maps-race.c b/tools/testing/selftests/proc/proc-maps-race.c
index 66773685a047..d40854a07ec1 100644
--- a/tools/testing/selftests/proc/proc-maps-race.c
+++ b/tools/testing/selftests/proc/proc-maps-race.c
@@ -32,6 +32,8 @@
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
+#include <linux/fs.h>
+#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/types.h>
@@ -317,6 +319,25 @@ static bool capture_mod_pattern(FIXTURE_DATA(proc_maps_race) *self,
strcmp(restored_first_line->text, self->first_line.text) == 0;
}
+static bool query_addr_at(int maps_fd, void *addr,
+ unsigned long *vma_start, unsigned long *vma_end)
+{
+ struct procmap_query q;
+
+ memset(&q, 0, sizeof(q));
+ q.size = sizeof(q);
+ /* Find the VMA at the split address */
+ q.query_addr = (unsigned long long)addr;
+ q.query_flags = 0;
+ if (ioctl(maps_fd, PROCMAP_QUERY, &q))
+ return false;
+
+ *vma_start = q.vma_start;
+ *vma_end = q.vma_end;
+
+ return true;
+}
+
static inline bool split_vma(FIXTURE_DATA(proc_maps_race) *self)
{
return mmap(self->mod_info->addr, self->page_size, self->mod_info->prot | PROT_EXEC,
@@ -559,6 +580,8 @@ TEST_F(proc_maps_race, test_maps_tearing_from_split)
do {
bool last_line_changed;
bool first_line_changed;
+ unsigned long vma_start;
+ unsigned long vma_end;
ASSERT_TRUE(read_boundary_lines(self, &new_last_line, &new_first_line));
@@ -595,6 +618,19 @@ TEST_F(proc_maps_race, test_maps_tearing_from_split)
first_line_changed = strcmp(new_first_line.text, self->first_line.text) != 0;
ASSERT_EQ(last_line_changed, first_line_changed);
+ /* Check if PROCMAP_QUERY ioclt() finds the right VMA */
+ ASSERT_TRUE(query_addr_at(self->maps_fd, mod_info->addr + self->page_size,
+ &vma_start, &vma_end));
+ /*
+ * The vma at the split address can be either the same as
+ * original one (if read before the split) or the same as the
+ * first line in the second page (if read after the split).
+ */
+ ASSERT_TRUE((vma_start == self->last_line.start_addr &&
+ vma_end == self->last_line.end_addr) ||
+ (vma_start == split_first_line.start_addr &&
+ vma_end == split_first_line.end_addr));
+
clock_gettime(CLOCK_MONOTONIC_COARSE, &end_ts);
end_test_iteration(&end_ts, self->verbose);
} while (end_ts.tv_sec - start_ts.tv_sec < self->duration_sec);
@@ -636,6 +672,9 @@ TEST_F(proc_maps_race, test_maps_tearing_from_resize)
clock_gettime(CLOCK_MONOTONIC_COARSE, &start_ts);
start_test_loop(&start_ts, self->verbose);
do {
+ unsigned long vma_start;
+ unsigned long vma_end;
+
ASSERT_TRUE(read_boundary_lines(self, &new_last_line, &new_first_line));
/* Check if we read vmas after shrinking it */
@@ -662,6 +701,16 @@ TEST_F(proc_maps_race, test_maps_tearing_from_resize)
"Expand result invalid", self));
}
+ /* Check if PROCMAP_QUERY ioclt() finds the right VMA */
+ ASSERT_TRUE(query_addr_at(self->maps_fd, mod_info->addr, &vma_start, &vma_end));
+ /*
+ * The vma should stay at the same address and have either the
+ * original size of 3 pages or 1 page if read after shrinking.
+ */
+ ASSERT_TRUE(vma_start == self->last_line.start_addr &&
+ (vma_end - vma_start == self->page_size * 3 ||
+ vma_end - vma_start == self->page_size));
+
clock_gettime(CLOCK_MONOTONIC_COARSE, &end_ts);
end_test_iteration(&end_ts, self->verbose);
} while (end_ts.tv_sec - start_ts.tv_sec < self->duration_sec);
@@ -703,6 +752,9 @@ TEST_F(proc_maps_race, test_maps_tearing_from_remap)
clock_gettime(CLOCK_MONOTONIC_COARSE, &start_ts);
start_test_loop(&start_ts, self->verbose);
do {
+ unsigned long vma_start;
+ unsigned long vma_end;
+
ASSERT_TRUE(read_boundary_lines(self, &new_last_line, &new_first_line));
/* Check if we read vmas after remapping it */
@@ -729,6 +781,19 @@ TEST_F(proc_maps_race, test_maps_tearing_from_remap)
"Remap restore result invalid", self));
}
+ /* Check if PROCMAP_QUERY ioclt() finds the right VMA */
+ ASSERT_TRUE(query_addr_at(self->maps_fd, mod_info->addr + self->page_size,
+ &vma_start, &vma_end));
+ /*
+ * The vma should either stay at the same address and have the
+ * original size of 3 pages or we should find the remapped vma
+ * at the remap destination address with size of 1 page.
+ */
+ ASSERT_TRUE((vma_start == self->last_line.start_addr &&
+ vma_end - vma_start == self->page_size * 3) ||
+ (vma_start == self->last_line.start_addr + self->page_size &&
+ vma_end - vma_start == self->page_size));
+
clock_gettime(CLOCK_MONOTONIC_COARSE, &end_ts);
end_test_iteration(&end_ts, self->verbose);
} while (end_ts.tv_sec - start_ts.tv_sec < self->duration_sec);
--
2.50.1.565.gc32cd1483b-goog
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