Re: [PATCH v3 5/6] kselftest: alloc_tag: add kselftest for ioctl interface

[Abhishek Bapat]

On Mon, Jun 8, 2026 at 11:27 PM Hao Ge <hao.ge@xxxxxxxxx> wrote:
>
>
> On 2026/6/9 14:09, Hao Ge wrote:
> > Hi Abhishek
> >
> >
> > On 2026/6/6 07:36, Abhishek Bapat wrote:
> >> Introduce a kselftest to verify the new IOCTL-based interface for
> >> /proc/allocinfo. The test covers:
> >>
> >> 1. Validation of the filename filter.
> >> 2. Validation of the function filter.
> >>
> >> The first test validates the functionality of the filename filter. Using
> >> "mm/memory.c" as the candidate filename filter, it retrieves filtered
> >> entries from both procfs and ioctl and matches the first VEC_MAX_ENTRIES
> >> entries.
> >>
> >> The second test validates the functionality of the function filter.
> >> It uses "dup_mm" as the candidate function as we do not expect this
> >> function name to change frequently and hence won't be needing to modify
> >> this test often.
> >>
> >> Note that both the tests match line no, function name and file name
> >> fields. Bytes allocated and calls are not matched as those values may
> >> change in the time when the data is being read from procfs and ioctl and
> >> hence can lead to false negatives.
> >>
> >> Signed-off-by: Abhishek Bapat <abhishekbapat@xxxxxxxxxx>
> >> ---
> >>   MAINTAINERS                                   |   1 +
> >>   tools/testing/selftests/alloc_tag/Makefile    |   9 +
> >>   .../alloc_tag/allocinfo_ioctl_test.c          | 313 ++++++++++++++++++
> >>   3 files changed, 323 insertions(+)
> >>   create mode 100644 tools/testing/selftests/alloc_tag/Makefile
> >>   create mode 100644
> >> tools/testing/selftests/alloc_tag/allocinfo_ioctl_test.c
> >>
> >> diff --git a/MAINTAINERS b/MAINTAINERS
> >> index 77f3fc487691..80560f5f1292 100644
> >> --- a/MAINTAINERS
> >> +++ b/MAINTAINERS
> >> @@ -16713,6 +16713,7 @@ F:    include/linux/alloc_tag.h
> >>   F:    include/linux/pgalloc_tag.h
> >>   F:    include/uapi/linux/alloc_tag.h
> >>   F:    lib/alloc_tag.c
> >> +F:    tools/testing/selftests/alloc_tag/
> >>     MEMORY CONTROLLER DRIVERS
> >>   M:    Krzysztof Kozlowski <krzk@xxxxxxxxxx>
> >> diff --git a/tools/testing/selftests/alloc_tag/Makefile
> >> b/tools/testing/selftests/alloc_tag/Makefile
> >> new file mode 100644
> >> index 000000000000..f2b8fc022c3b
> >> --- /dev/null
> >> +++ b/tools/testing/selftests/alloc_tag/Makefile
> >> @@ -0,0 +1,9 @@
> >> +# SPDX-License-Identifier: GPL-2.0
> >> +
> >> +TEST_GEN_PROGS := allocinfo_ioctl_test
> >> +
> >> +CFLAGS += -Wall
> >> +CFLAGS += -I../../../../usr/include
> >> +
> >> +include ../lib.mk
> >> +
> >> diff --git a/tools/testing/selftests/alloc_tag/allocinfo_ioctl_test.c
> >> b/tools/testing/selftests/alloc_tag/allocinfo_ioctl_test.c
> >> new file mode 100644
> >> index 000000000000..5c3c16e86c23
> >> --- /dev/null
> >> +++ b/tools/testing/selftests/alloc_tag/allocinfo_ioctl_test.c
> >> @@ -0,0 +1,313 @@
> >> +// SPDX-License-Identifier: GPL-2.0-only
> >> +
> >> +/* kselftest for allocinfo ioctl
> >> + * allocinfo ioctl retrives allocinfo data through ioctl
> >
> >
> > nit: s/retrives/retrieves/
> >
> >
> > I've applied the full patch series locally and ran the kselftest, all
> > 4 tests pass:
> >
> > [root@localhost alloc_tag]# ./allocinfo_ioctl_test
> > 1..4
> > ok 1 test_filename_filter
> > ok 2 test_function_filter
> > ok 3 test_size_filter
> > ok 4 test_lineno_filter
> > # Totals: pass:4 fail:0 xfail:0 xpass:0 skip:0 error:0
> >
> > But there are no tests for ALLOCINFO_FILTER_MASK_MODNAME and
> >
> > ALLOCINFO_FILTER_MASK_INACCURATE.
>
>
> Sorry, please disregard my suggestion about adding tests for
>
> ALLOCINFO_FILTER_MASK_MODNAME and ALLOCINFO_FILTER_MASK_INACCURATE.
>
> ALLOCINFO_FILTER_MASK_MODNAME depends on kernel config and also requires
>
> the module to be loaded. ALLOCINFO_FILTER_MASK_INACCURATE entries may not
>
> be common, unless we can find a stable way to produce them.
>
>
Ack, those are non-trivial to repro and hence we left them out.
> >
> >
> > Thanks
> >
> > Best Regards
> >
> > Hao
> >
> >> + * Copyright (C) 2026 Google, Inc.
> >> + */
> >> +
> >> +#include <errno.h>
> >> +#include <fcntl.h>
> >> +#include <stdio.h>
> >> +#include <stdlib.h>
> >> +#include <string.h>
> >> +#include <stdbool.h>
> >> +#include <unistd.h>
> >> +#include <sys/ioctl.h>
> >> +#include <linux/types.h>
> >> +#include <linux/alloc_tag.h>
> >> +#include "../kselftest.h"
> >> +
> >> +#define MAX_LINE_LEN        512
> >> +#define ALLOCINFO_PROC        "/proc/allocinfo"
> >> +
> >> +enum ioctl_ret {
> >> +    IOCTL_SUCCESS = 0,
> >> +    IOCTL_FAILURE = 1,
> >> +    IOCTL_INVALID_DATA = 2,
> >> +};
> >> +
> >> +#define VEC_MAX_ENTRIES 32
> >> +
> >> +struct allocinfo_tag_data_vec {
> >> +    struct allocinfo_tag_data tag[VEC_MAX_ENTRIES];
> >> +    __u64 count;
> >> +};
> >> +
> >> +static inline int __allocinfo_get_content_id(int dev_fd, struct
> >> allocinfo_content_id *params)
> >> +{
> >> +    return ioctl(dev_fd, ALLOCINFO_IOC_CONTENT_ID, params);
> >> +}
> >> +
> >> +static inline int __allocinfo_get_at(int dev_fd, struct
> >> allocinfo_get_at *params)
> >> +{
> >> +    return ioctl(dev_fd, ALLOCINFO_IOC_GET_AT, params);
> >> +}
> >> +
> >> +static inline int __allocinfo_get_next(int dev_fd, struct
> >> allocinfo_tag_data *params)
> >> +{
> >> +    return ioctl(dev_fd, ALLOCINFO_IOC_GET_NEXT, params);
> >> +}
> >> +
> >> +static bool match_entry(const struct allocinfo_tag_data *procfs_entry,
> >> +            const struct allocinfo_tag_data *tag_data,
> >> +            bool match_bytes, bool match_calls, bool match_lineno,
> >> +            bool match_function, bool match_filename)
> >> +{
> >> +    if (match_bytes && tag_data->counter.bytes !=
> >> procfs_entry->counter.bytes) {
> >> +        ksft_print_msg("size retrieved through ioctl does not match
> >> procfs\n");
> >> +        return false;
> >> +    }
> >> +
> >> +    if (match_calls && tag_data->counter.calls !=
> >> procfs_entry->counter.calls) {
> >> +        ksft_print_msg("call count retrieved through ioctl does not
> >> match procfs\n");
> >> +        return false;
> >> +    }
> >> +
> >> +    if (match_lineno && tag_data->tag.lineno !=
> >> procfs_entry->tag.lineno) {
> >> +        ksft_print_msg("lineno retrieved through ioctl does not
> >> match procfs\n");
> >> +        return false;
> >> +    }
> >> +
> >> +    if (match_function &&
> >> +        strncmp(tag_data->tag.function, procfs_entry->tag.function,
> >> ALLOCINFO_STR_SIZE)) {
> >> +        ksft_print_msg("function retrieved through ioctl does not
> >> match procfs\n");
> >> +        return false;
> >> +    }
> >> +
> >> +    if (match_filename &&
> >> +        strncmp(tag_data->tag.filename, procfs_entry->tag.filename,
> >> ALLOCINFO_STR_SIZE)) {
> >> +        ksft_print_msg("filename retrieved through ioctl does not
> >> match procfs\n");
> >> +        return false;
> >> +    }
> >> +    return true;
> >> +}
> >> +
> >> +static bool match_entries(const struct allocinfo_tag_data_vec
> >> *procfs_entries,
> >> +              const struct allocinfo_tag_data_vec *tags,
> >> +              bool match_bytes, bool match_calls, bool match_lineno,
> >> +              bool match_function, bool match_filename)
> >> +{
> >> +    __u64 i;
> >> +
> >> +    if (procfs_entries->count != tags->count) {
> >> +        ksft_print_msg("Entry count mismatch. ioctl entries: %llu,
> >> proc entries: %llu\n",
> >> +                   tags->count, procfs_entries->count);
> >> +        return false;
> >> +    }
> >> +    for (i = 0; i < procfs_entries->count; i++) {
> >> +        if (!match_entry(&procfs_entries->tag[i], &tags->tag[i],
> >> +                 match_bytes, match_calls, match_lineno,
> >> +                 match_function, match_filename)) {
> >> +            ksft_print_msg("%lluth entry does not match.\n", i);
> >> +            return false;
> >> +        }
> >> +    }
> >> +    return true;
> >> +}
> >> +
> >> +static int get_filtered_procfs_entries(struct allocinfo_tag_data_vec
> >> *procfs_entries,
> >> +                       const struct allocinfo_filter *filter, int fd)
> >> +{
> >> +    FILE *fp = fdopen(fd, "r");
> >> +    char line[MAX_LINE_LEN];
> >> +    int matches;
> >> +    struct allocinfo_tag_data procfs_entry;
> >> +
> >> +    if (!fp) {
> >> +        ksft_print_msg("Failed to open " ALLOCINFO_PROC " for
> >> reading\n");
> >> +        return 1;
> >> +    }
> >> +    memset(procfs_entries, 0, sizeof(*procfs_entries));
> >> +    while (fgets(line, sizeof(line), fp) && procfs_entries->count <
> >> VEC_MAX_ENTRIES) {
> >> +
> >> +        memset(&procfs_entry, 0, sizeof(procfs_entry));
> >> +        matches = sscanf(line, "%llu %llu %[^:]:%llu func:%s",
> >> +                 &procfs_entry.counter.bytes,
> >> +                 &procfs_entry.counter.calls,
> >> +                 procfs_entry.tag.filename,
> >> +                 &procfs_entry.tag.lineno,
> >> +                 procfs_entry.tag.function);
> >> +
> >> +        if (matches != 5)
> >> +            continue;
> >> +
> >> +        if (filter->mask & ALLOCINFO_FILTER_MASK_FILENAME) {
> >> +            if (strncmp(procfs_entry.tag.filename,
> >> +                    filter->fields.filename, ALLOCINFO_STR_SIZE))
> >> +                continue;
> >> +        }
> >> +        if (filter->mask & ALLOCINFO_FILTER_MASK_FUNCTION) {
> >> +            if (strncmp(procfs_entry.tag.function,
> >> +                    filter->fields.function, ALLOCINFO_STR_SIZE))
> >> +                continue;
> >> +        }
> >> +        if (filter->mask & ALLOCINFO_FILTER_MASK_LINENO) {
> >> +            if (procfs_entry.tag.lineno != filter->fields.lineno)
> >> +                continue;
> >> +        }
> >> +        if (filter->mask & ALLOCINFO_FILTER_MASK_MIN_SIZE) {
> >> +            if (procfs_entry.counter.bytes < filter->min_size)
> >> +                continue;
> >> +        }
> >> +        if (filter->mask & ALLOCINFO_FILTER_MASK_MAX_SIZE) {
> >> +            if (procfs_entry.counter.bytes > filter->max_size)
> >> +                continue;
> >> +        }
> >> +
> >> + memcpy(&procfs_entries->tag[procfs_entries->count++], &procfs_entry,
> >> +               sizeof(procfs_entry));
> >> +    }
> >> +    return 0;
> >> +}
> >> +
> >> +static enum ioctl_ret get_filtered_ioctl_entries(struct
> >> allocinfo_tag_data_vec *tags,
> >> +                         const struct allocinfo_filter *filter, int fd,
> >> +                         __u64 start_pos)
> >> +{
> >> +    struct allocinfo_content_id start_cont_id, end_cont_id;
> >> +    struct allocinfo_get_at get_at_params;
> >> +    const int max_retries = 10;
> >> +    int retry_count = 0;
> >> +    int status;
> >> +
> >> +    /*
> >> +     * __allocinfo_get_content_id may return different values if a
> >> kernel module was loaded
> >> +     * between the two calls. If that happens, the data gathered
> >> cannot be considered consistent
> >> +     * and hence needs to be fetched again to avoid flakiness.
> >> +     */
> >> +    do {
> >> +        if (__allocinfo_get_content_id(fd, &start_cont_id)) {
> >> +            ksft_print_msg("allocinfo_get_content_id failed\n");
> >> +            return IOCTL_FAILURE;
> >> +        }
> >> +
> >> +        memset(tags, 0, sizeof(*tags));
> >> +        memset(&get_at_params, 0, sizeof(get_at_params));
> >> +        memcpy(&get_at_params.filter, filter, sizeof(*filter));
> >> +        get_at_params.pos = start_pos;
> >> +        if (__allocinfo_get_at(fd, &get_at_params)) {
> >> +            ksft_print_msg("allocinfo_get_at failed\n");
> >> +            return IOCTL_FAILURE;
> >> +        }
> >> +        memcpy(&tags->tag[tags->count++], &get_at_params.data,
> >> sizeof(get_at_params.data));
> >> +
> >> +        while (tags->count < VEC_MAX_ENTRIES &&
> >> +               __allocinfo_get_next(fd, &tags->tag[tags->count]) == 0)
> >> +            tags->count++;
> >> +
> >> +        if (__allocinfo_get_content_id(fd, &end_cont_id)) {
> >> +            ksft_print_msg("allocinfo_get_content_id failed\n");
> >> +            return IOCTL_FAILURE;
> >> +        }
> >> +
> >> +        if (start_cont_id.id == end_cont_id.id) {
> >> +            status = IOCTL_SUCCESS;
> >> +        } else {
> >> +            ksft_print_msg("allocinfo_get_content_id mismatch,
> >> retrying...\n");
> >> +            status = IOCTL_INVALID_DATA;
> >> +        }
> >> +    } while (status == IOCTL_INVALID_DATA && retry_count++ <
> >> max_retries);
> >> +
> >> +    return status;
> >> +}
> >> +
> >> +static int run_filter_test(const struct allocinfo_filter *filter)
> >> +{
> >> +    int fd;
> >> +    struct allocinfo_tag_data_vec *tags = malloc(sizeof(*tags));
> >> +    struct allocinfo_tag_data_vec *procfs_entries =
> >> malloc(sizeof(*procfs_entries));
> >> +    int ioctl_status;
> >> +    int ret = KSFT_PASS;
> >> +
> >> +    if (!tags || !procfs_entries) {
> >> +        ksft_print_msg("Memory allocation failed.\n");
> >> +        ret = KSFT_FAIL;
> >> +        goto freemem;
> >> +    }
> >> +
> >> +    fd = open(ALLOCINFO_PROC, O_RDONLY);
> >> +    if (fd < 0) {
> >> +        ksft_exit_skip("Failed to open " ALLOCINFO_PROC ": %s\n",
> >> strerror(errno));
> >> +        ret = KSFT_FAIL;
> >> +        goto freemem;
> >> +    }
> >> +
> >> +    if (get_filtered_procfs_entries(procfs_entries, filter, fd)) {
> >> +        ksft_print_msg("Error retrieving entries from "
> >> ALLOCINFO_PROC "\n");
> >> +        ret = KSFT_FAIL;
> >> +        goto exit;
> >> +    }
> >> +
> >> +    if (procfs_entries->count == 0) {
> >> +        ksft_print_msg("No entries found in " ALLOCINFO_PROC ",
> >> skipping test\n");
> >> +        ret = KSFT_SKIP;
> >> +        goto exit;
> >> +    }
> >> +
> >> +    ioctl_status = get_filtered_ioctl_entries(tags, filter, fd, 0);
> >> +    if (ioctl_status == IOCTL_INVALID_DATA) {
> >> +        ksft_print_msg("Trouble retrieving valid IOCTL entries,
> >> skipping.\n");
> >> +        ret = KSFT_SKIP;
> >> +        goto exit;
> >> +    }
> >> +    if (ioctl_status == IOCTL_FAILURE) {
> >> +        ksft_print_msg("Error retrieving IOCTL entries.\n");
> >> +        ret = KSFT_FAIL;
> >> +        goto exit;
> >> +    }
> >> +
> >> +    if (!match_entries(procfs_entries, tags, false, false, true,
> >> true, true))
> >> +        ret = KSFT_FAIL;
> >> +
> >> +exit:
> >> +    close(fd);
> >> +freemem:
> >> +    free(tags);
> >> +    free(procfs_entries);
> >> +    return ret;
> >> +}
> >> +
> >> +static int test_filename_filter(void)
> >> +{
> >> +    struct allocinfo_filter filter;
> >> +    const char *target_filename = "mm/memory.c";
> >> +
> >> +    memset(&filter, 0, sizeof(filter));
> >> +    filter.mask |= ALLOCINFO_FILTER_MASK_FILENAME;
> >> +    strncpy(filter.fields.filename, target_filename,
> >> ALLOCINFO_STR_SIZE);
> >> +
> >> +    return run_filter_test(&filter);
> >> +}
> >> +
> >> +static int test_function_filter(void)
> >> +{
> >> +    struct allocinfo_filter filter;
> >> +    const char *target_function = "dup_mm";
> >> +
> >> +    memset(&filter, 0, sizeof(filter));
> >> +    filter.mask |= ALLOCINFO_FILTER_MASK_FUNCTION;
> >> +    strncpy(filter.fields.function, target_function,
> >> ALLOCINFO_STR_SIZE);
> >> +
> >> +    return run_filter_test(&filter);
> >> +}
> >> +
> >> +int main(int argc, char *argv[])
> >> +{
> >> +    int ret;
> >> +
> >> +    ksft_set_plan(2);
> >> +
> >> +    ret = test_filename_filter();
> >> +    if (ret == KSFT_SKIP)
> >> +        ksft_test_result_skip("Skipping test_filename_filter\n");
> >> +    else
> >> +        ksft_test_result(ret == KSFT_PASS, "test_filename_filter\n");
> >> +
> >> +    ret = test_function_filter();
> >> +    if (ret == KSFT_SKIP)
> >> +        ksft_test_result_skip("Skipping test_function_filter\n");
> >> +    else
> >> +        ksft_test_result(ret == KSFT_PASS, "test_function_filter\n");
> >> +
> >> +    ksft_finished();
> >> +}