Re: [PATCH v2] PM: hibernate: use acquire/release ordering when compress/decompress image

From: Rafael J. Wysocki
Date: Tue Dec 12 2023 - 08:04:09 EST

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On Thu, Nov 16, 2023 at 1:56 AM Hongchen Zhang
<zhanghongchen@xxxxxxxxxxx> wrote:
>
> When we test S4(suspend to disk) on LoongArch 3A6000 platform, the
> test case sometimes fails. The dmesg log shows the following error:
> Invalid LZO compressed length
> After we dig into the code, we find out that:
> When compress/decompress the image, the synchronization operation
> between the control thread and the compress/decompress/crc thread
> uses relaxed ordering interface, which is unreliable, and the
> following situation may occur:
> CPU 0 CPU 1
> save_image_lzo lzo_compress_threadfn
> atomic_set(&d->stop, 1);
> atomic_read(&data[thr].stop)
> data[thr].cmp = data[thr].cmp_len;
> WRITE data[thr].cmp_len
> Then CPU0 get a old cmp_len and write to disk. When cpu resume from S4,
> wrong cmp_len is loaded.
>
> To maintain data consistency between two threads, we should use the
> acquire/release ordering interface. So we change atomic_read/atomic_set
> to atomic_read_acquire/atomic_set_release.
>
> Fixes: 081a9d043c98 ("PM / Hibernate: Improve performance of LZO/plain hibernation, checksum image")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Hongchen Zhang <zhanghongchen@xxxxxxxxxxx>
> Signed-off-by: Weihao Li <liweihao@xxxxxxxxxxx>

I was about to apply this patch when I noticed the S-o-b confusion.

Either a From: header pointing to Weihao Li <liweihao@xxxxxxxxxxx> is
missing and the Hongchen Zhang <zhanghongchen@xxxxxxxxxxx> sign-off
means that the patch is sent on behalf of Weihao Li, or you both
worked on the patch together and a Co-developed-by: tag pointing to
Weihao Li <liweihao@xxxxxxxxxxx> is missing.

Which of the above is the case?

> ---
> v1 -> v2:
> 1. add Cc: stable@xxxxxxxxxxxxxxx in commit log
> 2. add Fixes: line in commit log
> ---
> kernel/power/swap.c | 38 +++++++++++++++++++-------------------
> 1 file changed, 19 insertions(+), 19 deletions(-)
>
> diff --git a/kernel/power/swap.c b/kernel/power/swap.c
> index a2cb0babb5ec..d44f5937f1e5 100644
> --- a/kernel/power/swap.c
> +++ b/kernel/power/swap.c
> @@ -606,11 +606,11 @@ static int crc32_threadfn(void *data)
> unsigned i;
>
> while (1) {
> - wait_event(d->go, atomic_read(&d->ready) ||
> + wait_event(d->go, atomic_read_acquire(&d->ready) ||
> kthread_should_stop());
> if (kthread_should_stop()) {
> d->thr = NULL;
> - atomic_set(&d->stop, 1);
> + atomic_set_release(&d->stop, 1);
> wake_up(&d->done);
> break;
> }
> @@ -619,7 +619,7 @@ static int crc32_threadfn(void *data)
> for (i = 0; i < d->run_threads; i++)
> *d->crc32 = crc32_le(*d->crc32,
> d->unc[i], *d->unc_len[i]);
> - atomic_set(&d->stop, 1);
> + atomic_set_release(&d->stop, 1);
> wake_up(&d->done);
> }
> return 0;
> @@ -649,12 +649,12 @@ static int lzo_compress_threadfn(void *data)
> struct cmp_data *d = data;
>
> while (1) {
> - wait_event(d->go, atomic_read(&d->ready) ||
> + wait_event(d->go, atomic_read_acquire(&d->ready) ||
> kthread_should_stop());
> if (kthread_should_stop()) {
> d->thr = NULL;
> d->ret = -1;
> - atomic_set(&d->stop, 1);
> + atomic_set_release(&d->stop, 1);
> wake_up(&d->done);
> break;
> }
> @@ -663,7 +663,7 @@ static int lzo_compress_threadfn(void *data)
> d->ret = lzo1x_1_compress(d->unc, d->unc_len,
> d->cmp + LZO_HEADER, &d->cmp_len,
> d->wrk);
> - atomic_set(&d->stop, 1);
> + atomic_set_release(&d->stop, 1);
> wake_up(&d->done);
> }
> return 0;
> @@ -798,7 +798,7 @@ static int save_image_lzo(struct swap_map_handle *handle,
>
> data[thr].unc_len = off;
>
> - atomic_set(&data[thr].ready, 1);
> + atomic_set_release(&data[thr].ready, 1);
> wake_up(&data[thr].go);
> }
>
> @@ -806,12 +806,12 @@ static int save_image_lzo(struct swap_map_handle *handle,
> break;
>
> crc->run_threads = thr;
> - atomic_set(&crc->ready, 1);
> + atomic_set_release(&crc->ready, 1);
> wake_up(&crc->go);
>
> for (run_threads = thr, thr = 0; thr < run_threads; thr++) {
> wait_event(data[thr].done,
> - atomic_read(&data[thr].stop));
> + atomic_read_acquire(&data[thr].stop));
> atomic_set(&data[thr].stop, 0);
>
> ret = data[thr].ret;
> @@ -850,7 +850,7 @@ static int save_image_lzo(struct swap_map_handle *handle,
> }
> }
>
> - wait_event(crc->done, atomic_read(&crc->stop));
> + wait_event(crc->done, atomic_read_acquire(&crc->stop));
> atomic_set(&crc->stop, 0);
> }
>
> @@ -1132,12 +1132,12 @@ static int lzo_decompress_threadfn(void *data)
> struct dec_data *d = data;
>
> while (1) {
> - wait_event(d->go, atomic_read(&d->ready) ||
> + wait_event(d->go, atomic_read_acquire(&d->ready) ||
> kthread_should_stop());
> if (kthread_should_stop()) {
> d->thr = NULL;
> d->ret = -1;
> - atomic_set(&d->stop, 1);
> + atomic_set_release(&d->stop, 1);
> wake_up(&d->done);
> break;
> }
> @@ -1150,7 +1150,7 @@ static int lzo_decompress_threadfn(void *data)
> flush_icache_range((unsigned long)d->unc,
> (unsigned long)d->unc + d->unc_len);
>
> - atomic_set(&d->stop, 1);
> + atomic_set_release(&d->stop, 1);
> wake_up(&d->done);
> }
> return 0;
> @@ -1335,7 +1335,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
> }
>
> if (crc->run_threads) {
> - wait_event(crc->done, atomic_read(&crc->stop));
> + wait_event(crc->done, atomic_read_acquire(&crc->stop));
> atomic_set(&crc->stop, 0);
> crc->run_threads = 0;
> }
> @@ -1371,7 +1371,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
> pg = 0;
> }
>
> - atomic_set(&data[thr].ready, 1);
> + atomic_set_release(&data[thr].ready, 1);
> wake_up(&data[thr].go);
> }
>
> @@ -1390,7 +1390,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
>
> for (run_threads = thr, thr = 0; thr < run_threads; thr++) {
> wait_event(data[thr].done,
> - atomic_read(&data[thr].stop));
> + atomic_read_acquire(&data[thr].stop));
> atomic_set(&data[thr].stop, 0);
>
> ret = data[thr].ret;
> @@ -1421,7 +1421,7 @@ static int load_image_lzo(struct swap_map_handle *handle,
> ret = snapshot_write_next(snapshot);
> if (ret <= 0) {
> crc->run_threads = thr + 1;
> - atomic_set(&crc->ready, 1);
> + atomic_set_release(&crc->ready, 1);
> wake_up(&crc->go);
> goto out_finish;
> }
> @@ -1429,13 +1429,13 @@ static int load_image_lzo(struct swap_map_handle *handle,
> }
>
> crc->run_threads = thr;
> - atomic_set(&crc->ready, 1);
> + atomic_set_release(&crc->ready, 1);
> wake_up(&crc->go);
> }
>
> out_finish:
> if (crc->run_threads) {
> - wait_event(crc->done, atomic_read(&crc->stop));
> + wait_event(crc->done, atomic_read_acquire(&crc->stop));
> atomic_set(&crc->stop, 0);
> }
> stop = ktime_get();
> --
> 2.33.0
>

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Next in thread: Hongchen Zhang: "Re: [PATCH v2] PM: hibernate: use acquire/release ordering when compress/decompress image"
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