* [PATCH v2] zram: fix incorrectly stat with failed_reads
@ 2014-08-13 2:01 Chao Yu
2014-08-13 8:31 ` Jerome Marchand
2014-08-14 0:26 ` Minchan Kim
0 siblings, 2 replies; 8+ messages in thread
From: Chao Yu @ 2014-08-13 2:01 UTC (permalink / raw)
To: minchan
Cc: ngupta, linux-kernel, 'Jerome Marchand',
'Sergey Senozhatsky', 'Andrew Morton'
Since we allocate a temporary buffer in zram_bvec_read to handle partial page
operations in this commit 924bd88d703e53d30f393fac6117f8f1bc79aab6 (Staging:
zram: allow partial page operations), our ->failed_reads value may be incorrect
as we do not increase its value when failed to allocate the temporary buffer.
Let's fix this issue and correct the annotation of failed_reads.
v2: clean codes of failed_{reads,writes} stat pointed out by Minchan Kim, and
this cleanup also fix incorrectly stat when fail in zram_decompress_page.
Signed-off-by: Chao Yu <chao2.yu@samsung.com>
---
drivers/block/zram/zram_drv.c | 10 +++++++---
drivers/block/zram/zram_drv.h | 2 +-
2 files changed, 8 insertions(+), 4 deletions(-)
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
index dfa4024..d00831c 100644
--- a/drivers/block/zram/zram_drv.c
+++ b/drivers/block/zram/zram_drv.c
@@ -378,7 +378,6 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index)
/* Should NEVER happen. Return bio error if it does. */
if (unlikely(ret)) {
pr_err("Decompression failed! err=%d, page=%u\n", ret, index);
- atomic64_inc(&zram->stats.failed_reads);
return ret;
}
@@ -547,8 +546,6 @@ out:
zcomp_strm_release(zram->comp, zstrm);
if (is_partial_io(bvec))
kfree(uncmem);
- if (ret)
- atomic64_inc(&zram->stats.failed_writes);
return ret;
}
@@ -566,6 +563,13 @@ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index,
ret = zram_bvec_write(zram, bvec, index, offset);
}
+ if (unlikely(ret)) {
+ if (rw == READ)
+ atomic64_inc(&zram->stats.failed_reads);
+ else
+ atomic64_inc(&zram->stats.failed_writes);
+ }
+
return ret;
}
diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
index 5b0afde..e0f725c 100644
--- a/drivers/block/zram/zram_drv.h
+++ b/drivers/block/zram/zram_drv.h
@@ -84,7 +84,7 @@ struct zram_stats {
atomic64_t compr_data_size; /* compressed size of pages stored */
atomic64_t num_reads; /* failed + successful */
atomic64_t num_writes; /* --do-- */
- atomic64_t failed_reads; /* should NEVER! happen */
+ atomic64_t failed_reads; /* can happen when memory is too low */
atomic64_t failed_writes; /* can happen when memory is too low */
atomic64_t invalid_io; /* non-page-aligned I/O requests */
atomic64_t notify_free; /* no. of swap slot free notifications */
--
2.0.1.474.g72c7794
^ permalink raw reply related [flat|nested] 8+ messages in thread* Re: [PATCH v2] zram: fix incorrectly stat with failed_reads 2014-08-13 2:01 [PATCH v2] zram: fix incorrectly stat with failed_reads Chao Yu @ 2014-08-13 8:31 ` Jerome Marchand 2014-08-13 11:32 ` Sergey Senozhatsky 2014-08-14 0:26 ` Minchan Kim 1 sibling, 1 reply; 8+ messages in thread From: Jerome Marchand @ 2014-08-13 8:31 UTC (permalink / raw) To: Chao Yu, minchan Cc: ngupta, linux-kernel, 'Sergey Senozhatsky', 'Andrew Morton' [-- Attachment #1: Type: text/plain, Size: 2694 bytes --] On 08/13/2014 04:01 AM, Chao Yu wrote: > Since we allocate a temporary buffer in zram_bvec_read to handle partial page > operations in this commit 924bd88d703e53d30f393fac6117f8f1bc79aab6 (Staging: > zram: allow partial page operations), our ->failed_reads value may be incorrect > as we do not increase its value when failed to allocate the temporary buffer. > > Let's fix this issue and correct the annotation of failed_reads. > > v2: clean codes of failed_{reads,writes} stat pointed out by Minchan Kim, and > this cleanup also fix incorrectly stat when fail in zram_decompress_page. > > Signed-off-by: Chao Yu <chao2.yu@samsung.com> Acked-by: Jerome Marchand <jmarchan@redhat.com> > --- > drivers/block/zram/zram_drv.c | 10 +++++++--- > drivers/block/zram/zram_drv.h | 2 +- > 2 files changed, 8 insertions(+), 4 deletions(-) > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > index dfa4024..d00831c 100644 > --- a/drivers/block/zram/zram_drv.c > +++ b/drivers/block/zram/zram_drv.c > @@ -378,7 +378,6 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index) > /* Should NEVER happen. Return bio error if it does. */ > if (unlikely(ret)) { > pr_err("Decompression failed! err=%d, page=%u\n", ret, index); > - atomic64_inc(&zram->stats.failed_reads); > return ret; > } > > @@ -547,8 +546,6 @@ out: > zcomp_strm_release(zram->comp, zstrm); > if (is_partial_io(bvec)) > kfree(uncmem); > - if (ret) > - atomic64_inc(&zram->stats.failed_writes); > return ret; > } > > @@ -566,6 +563,13 @@ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index, > ret = zram_bvec_write(zram, bvec, index, offset); > } > > + if (unlikely(ret)) { > + if (rw == READ) > + atomic64_inc(&zram->stats.failed_reads); > + else > + atomic64_inc(&zram->stats.failed_writes); > + } > + > return ret; > } > > diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h > index 5b0afde..e0f725c 100644 > --- a/drivers/block/zram/zram_drv.h > +++ b/drivers/block/zram/zram_drv.h > @@ -84,7 +84,7 @@ struct zram_stats { > atomic64_t compr_data_size; /* compressed size of pages stored */ > atomic64_t num_reads; /* failed + successful */ > atomic64_t num_writes; /* --do-- */ > - atomic64_t failed_reads; /* should NEVER! happen */ > + atomic64_t failed_reads; /* can happen when memory is too low */ > atomic64_t failed_writes; /* can happen when memory is too low */ > atomic64_t invalid_io; /* non-page-aligned I/O requests */ > atomic64_t notify_free; /* no. of swap slot free notifications */ > [-- Attachment #2: OpenPGP digital signature --] [-- Type: application/pgp-signature, Size: 538 bytes --] ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] zram: fix incorrectly stat with failed_reads 2014-08-13 8:31 ` Jerome Marchand @ 2014-08-13 11:32 ` Sergey Senozhatsky 2014-08-13 14:43 ` Sergey Senozhatsky 0 siblings, 1 reply; 8+ messages in thread From: Sergey Senozhatsky @ 2014-08-13 11:32 UTC (permalink / raw) To: Jerome Marchand Cc: Chao Yu, minchan, ngupta, linux-kernel, 'Sergey Senozhatsky', 'Andrew Morton' On (08/13/14 10:31), Jerome Marchand wrote: > Date: Wed, 13 Aug 2014 10:31:45 +0200 > From: Jerome Marchand <jmarchan@redhat.com> > To: Chao Yu <chao2.yu@samsung.com>, minchan@kernel.org > CC: ngupta@vflare.org, linux-kernel@vger.kernel.org, 'Sergey Senozhatsky' > <sergey.senozhatsky@gmail.com>, 'Andrew Morton' > <akpm@linux-foundation.org> > Subject: Re: [PATCH v2] zram: fix incorrectly stat with failed_reads > User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 > Thunderbird/24.6.0 > > On 08/13/2014 04:01 AM, Chao Yu wrote: > > Since we allocate a temporary buffer in zram_bvec_read to handle partial page > > operations in this commit 924bd88d703e53d30f393fac6117f8f1bc79aab6 (Staging: > > zram: allow partial page operations), our ->failed_reads value may be incorrect > > as we do not increase its value when failed to allocate the temporary buffer. > > > > Let's fix this issue and correct the annotation of failed_reads. > > > > v2: clean codes of failed_{reads,writes} stat pointed out by Minchan Kim, and > > this cleanup also fix incorrectly stat when fail in zram_decompress_page. > > > > Signed-off-by: Chao Yu <chao2.yu@samsung.com> > > Acked-by: Jerome Marchand <jmarchan@redhat.com> Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> -ss > > --- > > drivers/block/zram/zram_drv.c | 10 +++++++--- > > drivers/block/zram/zram_drv.h | 2 +- > > 2 files changed, 8 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > > index dfa4024..d00831c 100644 > > --- a/drivers/block/zram/zram_drv.c > > +++ b/drivers/block/zram/zram_drv.c > > @@ -378,7 +378,6 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index) > > /* Should NEVER happen. Return bio error if it does. */ > > if (unlikely(ret)) { > > pr_err("Decompression failed! err=%d, page=%u\n", ret, index); > > - atomic64_inc(&zram->stats.failed_reads); > > return ret; > > } > > > > @@ -547,8 +546,6 @@ out: > > zcomp_strm_release(zram->comp, zstrm); > > if (is_partial_io(bvec)) > > kfree(uncmem); > > - if (ret) > > - atomic64_inc(&zram->stats.failed_writes); > > return ret; > > } > > > > @@ -566,6 +563,13 @@ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index, > > ret = zram_bvec_write(zram, bvec, index, offset); > > } > > > > + if (unlikely(ret)) { > > + if (rw == READ) > > + atomic64_inc(&zram->stats.failed_reads); > > + else > > + atomic64_inc(&zram->stats.failed_writes); > > + } > > + > > return ret; > > } > > > > diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h > > index 5b0afde..e0f725c 100644 > > --- a/drivers/block/zram/zram_drv.h > > +++ b/drivers/block/zram/zram_drv.h > > @@ -84,7 +84,7 @@ struct zram_stats { > > atomic64_t compr_data_size; /* compressed size of pages stored */ > > atomic64_t num_reads; /* failed + successful */ > > atomic64_t num_writes; /* --do-- */ > > - atomic64_t failed_reads; /* should NEVER! happen */ > > + atomic64_t failed_reads; /* can happen when memory is too low */ > > atomic64_t failed_writes; /* can happen when memory is too low */ > > atomic64_t invalid_io; /* non-page-aligned I/O requests */ > > atomic64_t notify_free; /* no. of swap slot free notifications */ > > > > ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] zram: fix incorrectly stat with failed_reads 2014-08-13 11:32 ` Sergey Senozhatsky @ 2014-08-13 14:43 ` Sergey Senozhatsky 2014-08-13 14:49 ` Sergey Senozhatsky 2014-08-13 23:02 ` Minchan Kim 0 siblings, 2 replies; 8+ messages in thread From: Sergey Senozhatsky @ 2014-08-13 14:43 UTC (permalink / raw) To: Minchan Kim Cc: Jerome Marchand, Chao Yu, Nitin Gupta, linux-kernel, Sergey Senozhatsky Hello, On (08/13/14 20:32), Sergey Senozhatsky wrote: > On (08/13/14 10:31), Jerome Marchand wrote: > > Date: Wed, 13 Aug 2014 10:31:45 +0200 > > From: Jerome Marchand <jmarchan@redhat.com> > > To: Chao Yu <chao2.yu@samsung.com>, minchan@kernel.org > > CC: ngupta@vflare.org, linux-kernel@vger.kernel.org, 'Sergey Senozhatsky' > > <sergey.senozhatsky@gmail.com>, 'Andrew Morton' > > <akpm@linux-foundation.org> > > Subject: Re: [PATCH v2] zram: fix incorrectly stat with failed_reads > > User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 > > Thunderbird/24.6.0 > > > > On 08/13/2014 04:01 AM, Chao Yu wrote: > > > Since we allocate a temporary buffer in zram_bvec_read to handle partial page > > > operations in this commit 924bd88d703e53d30f393fac6117f8f1bc79aab6 (Staging: > > > zram: allow partial page operations), our ->failed_reads value may be incorrect > > > as we do not increase its value when failed to allocate the temporary buffer. > > > > > > Let's fix this issue and correct the annotation of failed_reads. > > > > > > v2: clean codes of failed_{reads,writes} stat pointed out by Minchan Kim, and > > > this cleanup also fix incorrectly stat when fail in zram_decompress_page. > > > > > > Signed-off-by: Chao Yu <chao2.yu@samsung.com> > > > > Acked-by: Jerome Marchand <jmarchan@redhat.com> > > Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> > > -ss > > > > --- > > > drivers/block/zram/zram_drv.c | 10 +++++++--- > > > drivers/block/zram/zram_drv.h | 2 +- > > > 2 files changed, 8 insertions(+), 4 deletions(-) > > > > > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > > > index dfa4024..d00831c 100644 > > > --- a/drivers/block/zram/zram_drv.c > > > +++ b/drivers/block/zram/zram_drv.c > > > @@ -378,7 +378,6 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index) > > > /* Should NEVER happen. Return bio error if it does. */ > > > if (unlikely(ret)) { > > > pr_err("Decompression failed! err=%d, page=%u\n", ret, index); > > > - atomic64_inc(&zram->stats.failed_reads); > > > return ret; > > > } > > > > > > @@ -547,8 +546,6 @@ out: > > > zcomp_strm_release(zram->comp, zstrm); > > > if (is_partial_io(bvec)) > > > kfree(uncmem); > > > - if (ret) > > > - atomic64_inc(&zram->stats.failed_writes); > > > return ret; > > > } > > > > > > @@ -566,6 +563,13 @@ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index, > > > ret = zram_bvec_write(zram, bvec, index, offset); > > > } > > > > > > + if (unlikely(ret)) { > > > + if (rw == READ) > > > + atomic64_inc(&zram->stats.failed_reads); > > > + else > > > + atomic64_inc(&zram->stats.failed_writes); > > > + } > > > + > > > return ret; > > > } > > > > > > diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h > > > index 5b0afde..e0f725c 100644 > > > --- a/drivers/block/zram/zram_drv.h > > > +++ b/drivers/block/zram/zram_drv.h > > > @@ -84,7 +84,7 @@ struct zram_stats { > > > atomic64_t compr_data_size; /* compressed size of pages stored */ > > > atomic64_t num_reads; /* failed + successful */ > > > atomic64_t num_writes; /* --do-- */ > > > - atomic64_t failed_reads; /* should NEVER! happen */ > > > + atomic64_t failed_reads; /* can happen when memory is too low */ this grabbed my attention. "failed_writes; /* can happen when memory is too low */" theoretically, we can have a misbehaving compression algorithm. so the question is -- should we fail write() if compression has failed for any other reason, rather than -ENOMEM? alternatively, we can store uncompressed user mem, just the same way we do for `badly' compressed buffers, set a FAILED_COMPRESSION flag (so we will not leak kernel memory on read() if we failed to compress is_partial_io() bv_page), and on read() copy it out as is, just as we do for `badly' compessed pages. so, what do you think? /* I can take a look on it */ -ss > > > atomic64_t failed_writes; /* can happen when memory is too low */ > > > atomic64_t invalid_io; /* non-page-aligned I/O requests */ > > > atomic64_t notify_free; /* no. of swap slot free notifications */ > > > > > > > > > ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] zram: fix incorrectly stat with failed_reads 2014-08-13 14:43 ` Sergey Senozhatsky @ 2014-08-13 14:49 ` Sergey Senozhatsky 2014-08-13 23:02 ` Minchan Kim 1 sibling, 0 replies; 8+ messages in thread From: Sergey Senozhatsky @ 2014-08-13 14:49 UTC (permalink / raw) To: Sergey Senozhatsky Cc: Minchan Kim, Jerome Marchand, Chao Yu, Nitin Gupta, linux-kernel On (08/13/14 23:43), Sergey Senozhatsky wrote: > Hello, > > On (08/13/14 20:32), Sergey Senozhatsky wrote: > > On (08/13/14 10:31), Jerome Marchand wrote: > > > Date: Wed, 13 Aug 2014 10:31:45 +0200 > > > From: Jerome Marchand <jmarchan@redhat.com> > > > To: Chao Yu <chao2.yu@samsung.com>, minchan@kernel.org > > > CC: ngupta@vflare.org, linux-kernel@vger.kernel.org, 'Sergey Senozhatsky' > > > <sergey.senozhatsky@gmail.com>, 'Andrew Morton' > > > <akpm@linux-foundation.org> > > > Subject: Re: [PATCH v2] zram: fix incorrectly stat with failed_reads > > > User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 > > > Thunderbird/24.6.0 > > > > > > On 08/13/2014 04:01 AM, Chao Yu wrote: > > > > Since we allocate a temporary buffer in zram_bvec_read to handle partial page > > > > operations in this commit 924bd88d703e53d30f393fac6117f8f1bc79aab6 (Staging: > > > > zram: allow partial page operations), our ->failed_reads value may be incorrect > > > > as we do not increase its value when failed to allocate the temporary buffer. > > > > > > > > Let's fix this issue and correct the annotation of failed_reads. > > > > > > > > v2: clean codes of failed_{reads,writes} stat pointed out by Minchan Kim, and > > > > this cleanup also fix incorrectly stat when fail in zram_decompress_page. > > > > > > > > Signed-off-by: Chao Yu <chao2.yu@samsung.com> > > > > > > Acked-by: Jerome Marchand <jmarchan@redhat.com> > > > > Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> > > > > -ss > > > > > > --- > > > > drivers/block/zram/zram_drv.c | 10 +++++++--- > > > > drivers/block/zram/zram_drv.h | 2 +- > > > > 2 files changed, 8 insertions(+), 4 deletions(-) > > > > > > > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > > > > index dfa4024..d00831c 100644 > > > > --- a/drivers/block/zram/zram_drv.c > > > > +++ b/drivers/block/zram/zram_drv.c > > > > @@ -378,7 +378,6 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index) > > > > /* Should NEVER happen. Return bio error if it does. */ > > > > if (unlikely(ret)) { > > > > pr_err("Decompression failed! err=%d, page=%u\n", ret, index); > > > > - atomic64_inc(&zram->stats.failed_reads); > > > > return ret; > > > > } > > > > > > > > @@ -547,8 +546,6 @@ out: > > > > zcomp_strm_release(zram->comp, zstrm); > > > > if (is_partial_io(bvec)) > > > > kfree(uncmem); > > > > - if (ret) > > > > - atomic64_inc(&zram->stats.failed_writes); > > > > return ret; > > > > } > > > > > > > > @@ -566,6 +563,13 @@ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index, > > > > ret = zram_bvec_write(zram, bvec, index, offset); > > > > } > > > > > > > > + if (unlikely(ret)) { > > > > + if (rw == READ) > > > > + atomic64_inc(&zram->stats.failed_reads); > > > > + else > > > > + atomic64_inc(&zram->stats.failed_writes); > > > > + } > > > > + > > > > return ret; > > > > } > > > > > > > > diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h > > > > index 5b0afde..e0f725c 100644 > > > > --- a/drivers/block/zram/zram_drv.h > > > > +++ b/drivers/block/zram/zram_drv.h > > > > @@ -84,7 +84,7 @@ struct zram_stats { > > > > atomic64_t compr_data_size; /* compressed size of pages stored */ > > > > atomic64_t num_reads; /* failed + successful */ > > > > atomic64_t num_writes; /* --do-- */ > > > > - atomic64_t failed_reads; /* should NEVER! happen */ > > > > + atomic64_t failed_reads; /* can happen when memory is too low */ > > > this grabbed my attention. > > "failed_writes; /* can happen when memory is too low */" > > theoretically, we can have a misbehaving compression algorithm. so the > question is -- should we fail write() if compression has failed for any > other reason, rather than -ENOMEM? alternatively, we can store uncompressed > user mem, just the same way we do for `badly' compressed buffers, set a > FAILED_COMPRESSION flag (so we will not leak kernel memory on read() if we > failed to compress is_partial_io() bv_page), and on read() copy it out as is, > just as we do for `badly' compessed pages. > though this will surely complicate both write() and read() paths, but still. -ss > so, what do you think? /* I can take a look on it */ > > -ss > > > > > atomic64_t failed_writes; /* can happen when memory is too low */ > > > > atomic64_t invalid_io; /* non-page-aligned I/O requests */ > > > > atomic64_t notify_free; /* no. of swap slot free notifications */ > > > > > > > > > > > > > > > ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] zram: fix incorrectly stat with failed_reads 2014-08-13 14:43 ` Sergey Senozhatsky 2014-08-13 14:49 ` Sergey Senozhatsky @ 2014-08-13 23:02 ` Minchan Kim 2014-08-14 12:54 ` Sergey Senozhatsky 1 sibling, 1 reply; 8+ messages in thread From: Minchan Kim @ 2014-08-13 23:02 UTC (permalink / raw) To: Sergey Senozhatsky; +Cc: Jerome Marchand, Chao Yu, Nitin Gupta, linux-kernel Hi Sergey, On Wed, Aug 13, 2014 at 11:43:04PM +0900, Sergey Senozhatsky wrote: > Hello, > > On (08/13/14 20:32), Sergey Senozhatsky wrote: > > On (08/13/14 10:31), Jerome Marchand wrote: > > > Date: Wed, 13 Aug 2014 10:31:45 +0200 > > > From: Jerome Marchand <jmarchan@redhat.com> > > > To: Chao Yu <chao2.yu@samsung.com>, minchan@kernel.org > > > CC: ngupta@vflare.org, linux-kernel@vger.kernel.org, 'Sergey Senozhatsky' > > > <sergey.senozhatsky@gmail.com>, 'Andrew Morton' > > > <akpm@linux-foundation.org> > > > Subject: Re: [PATCH v2] zram: fix incorrectly stat with failed_reads > > > User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 > > > Thunderbird/24.6.0 > > > > > > On 08/13/2014 04:01 AM, Chao Yu wrote: > > > > Since we allocate a temporary buffer in zram_bvec_read to handle partial page > > > > operations in this commit 924bd88d703e53d30f393fac6117f8f1bc79aab6 (Staging: > > > > zram: allow partial page operations), our ->failed_reads value may be incorrect > > > > as we do not increase its value when failed to allocate the temporary buffer. > > > > > > > > Let's fix this issue and correct the annotation of failed_reads. > > > > > > > > v2: clean codes of failed_{reads,writes} stat pointed out by Minchan Kim, and > > > > this cleanup also fix incorrectly stat when fail in zram_decompress_page. > > > > > > > > Signed-off-by: Chao Yu <chao2.yu@samsung.com> > > > > > > Acked-by: Jerome Marchand <jmarchan@redhat.com> > > > > Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> > > > > -ss > > > > > > --- > > > > drivers/block/zram/zram_drv.c | 10 +++++++--- > > > > drivers/block/zram/zram_drv.h | 2 +- > > > > 2 files changed, 8 insertions(+), 4 deletions(-) > > > > > > > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > > > > index dfa4024..d00831c 100644 > > > > --- a/drivers/block/zram/zram_drv.c > > > > +++ b/drivers/block/zram/zram_drv.c > > > > @@ -378,7 +378,6 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index) > > > > /* Should NEVER happen. Return bio error if it does. */ > > > > if (unlikely(ret)) { > > > > pr_err("Decompression failed! err=%d, page=%u\n", ret, index); > > > > - atomic64_inc(&zram->stats.failed_reads); > > > > return ret; > > > > } > > > > > > > > @@ -547,8 +546,6 @@ out: > > > > zcomp_strm_release(zram->comp, zstrm); > > > > if (is_partial_io(bvec)) > > > > kfree(uncmem); > > > > - if (ret) > > > > - atomic64_inc(&zram->stats.failed_writes); > > > > return ret; > > > > } > > > > > > > > @@ -566,6 +563,13 @@ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index, > > > > ret = zram_bvec_write(zram, bvec, index, offset); > > > > } > > > > > > > > + if (unlikely(ret)) { > > > > + if (rw == READ) > > > > + atomic64_inc(&zram->stats.failed_reads); > > > > + else > > > > + atomic64_inc(&zram->stats.failed_writes); > > > > + } > > > > + > > > > return ret; > > > > } > > > > > > > > diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h > > > > index 5b0afde..e0f725c 100644 > > > > --- a/drivers/block/zram/zram_drv.h > > > > +++ b/drivers/block/zram/zram_drv.h > > > > @@ -84,7 +84,7 @@ struct zram_stats { > > > > atomic64_t compr_data_size; /* compressed size of pages stored */ > > > > atomic64_t num_reads; /* failed + successful */ > > > > atomic64_t num_writes; /* --do-- */ > > > > - atomic64_t failed_reads; /* should NEVER! happen */ > > > > + atomic64_t failed_reads; /* can happen when memory is too low */ > > > this grabbed my attention. > > "failed_writes; /* can happen when memory is too low */" > > theoretically, we can have a misbehaving compression algorithm. so the > question is -- should we fail write() if compression has failed for any > other reason, rather than -ENOMEM? alternatively, we can store uncompressed > user mem, just the same way we do for `badly' compressed buffers, set a > FAILED_COMPRESSION flag (so we will not leak kernel memory on read() if we > failed to compress is_partial_io() bv_page), and on read() copy it out as is, > just as we do for `badly' compessed pages. > > so, what do you think? /* I can take a look on it */ How often does it happen? I don't think it's valuable to maintain if it's too rare. Rather, I'd like to remove the comment on failed_writes. :) > > -ss > > > > > atomic64_t failed_writes; /* can happen when memory is too low */ > > > > atomic64_t invalid_io; /* non-page-aligned I/O requests */ > > > > atomic64_t notify_free; /* no. of swap slot free notifications */ > > > > > > > > > > > > > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- Kind regards, Minchan Kim ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] zram: fix incorrectly stat with failed_reads 2014-08-13 23:02 ` Minchan Kim @ 2014-08-14 12:54 ` Sergey Senozhatsky 0 siblings, 0 replies; 8+ messages in thread From: Sergey Senozhatsky @ 2014-08-14 12:54 UTC (permalink / raw) To: Minchan Kim Cc: Sergey Senozhatsky, Jerome Marchand, Chao Yu, Nitin Gupta, linux-kernel Hi, On (08/14/14 08:02), Minchan Kim wrote: > On Wed, Aug 13, 2014 at 11:43:04PM +0900, Sergey Senozhatsky wrote: > > Hello, > > > > On (08/13/14 20:32), Sergey Senozhatsky wrote: > > > On (08/13/14 10:31), Jerome Marchand wrote: > > > > Date: Wed, 13 Aug 2014 10:31:45 +0200 > > > > From: Jerome Marchand <jmarchan@redhat.com> > > > > To: Chao Yu <chao2.yu@samsung.com>, minchan@kernel.org > > > > CC: ngupta@vflare.org, linux-kernel@vger.kernel.org, 'Sergey Senozhatsky' > > > > <sergey.senozhatsky@gmail.com>, 'Andrew Morton' > > > > <akpm@linux-foundation.org> > > > > Subject: Re: [PATCH v2] zram: fix incorrectly stat with failed_reads > > > > User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 > > > > Thunderbird/24.6.0 > > > > > > > > On 08/13/2014 04:01 AM, Chao Yu wrote: > > > > > Since we allocate a temporary buffer in zram_bvec_read to handle partial page > > > > > operations in this commit 924bd88d703e53d30f393fac6117f8f1bc79aab6 (Staging: > > > > > zram: allow partial page operations), our ->failed_reads value may be incorrect > > > > > as we do not increase its value when failed to allocate the temporary buffer. > > > > > > > > > > Let's fix this issue and correct the annotation of failed_reads. > > > > > > > > > > v2: clean codes of failed_{reads,writes} stat pointed out by Minchan Kim, and > > > > > this cleanup also fix incorrectly stat when fail in zram_decompress_page. > > > > > > > > > > Signed-off-by: Chao Yu <chao2.yu@samsung.com> > > > > > > > > Acked-by: Jerome Marchand <jmarchan@redhat.com> > > > > > > Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> > > > > > > -ss > > > > > > > > --- > > > > > drivers/block/zram/zram_drv.c | 10 +++++++--- > > > > > drivers/block/zram/zram_drv.h | 2 +- > > > > > 2 files changed, 8 insertions(+), 4 deletions(-) > > > > > > > > > > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > > > > > index dfa4024..d00831c 100644 > > > > > --- a/drivers/block/zram/zram_drv.c > > > > > +++ b/drivers/block/zram/zram_drv.c > > > > > @@ -378,7 +378,6 @@ static int zram_decompress_page(struct zram *zram, char *mem, u32 index) > > > > > /* Should NEVER happen. Return bio error if it does. */ > > > > > if (unlikely(ret)) { > > > > > pr_err("Decompression failed! err=%d, page=%u\n", ret, index); > > > > > - atomic64_inc(&zram->stats.failed_reads); > > > > > return ret; > > > > > } > > > > > > > > > > @@ -547,8 +546,6 @@ out: > > > > > zcomp_strm_release(zram->comp, zstrm); > > > > > if (is_partial_io(bvec)) > > > > > kfree(uncmem); > > > > > - if (ret) > > > > > - atomic64_inc(&zram->stats.failed_writes); > > > > > return ret; > > > > > } > > > > > > > > > > @@ -566,6 +563,13 @@ static int zram_bvec_rw(struct zram *zram, struct bio_vec *bvec, u32 index, > > > > > ret = zram_bvec_write(zram, bvec, index, offset); > > > > > } > > > > > > > > > > + if (unlikely(ret)) { > > > > > + if (rw == READ) > > > > > + atomic64_inc(&zram->stats.failed_reads); > > > > > + else > > > > > + atomic64_inc(&zram->stats.failed_writes); > > > > > + } > > > > > + > > > > > return ret; > > > > > } > > > > > > > > > > diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h > > > > > index 5b0afde..e0f725c 100644 > > > > > --- a/drivers/block/zram/zram_drv.h > > > > > +++ b/drivers/block/zram/zram_drv.h > > > > > @@ -84,7 +84,7 @@ struct zram_stats { > > > > > atomic64_t compr_data_size; /* compressed size of pages stored */ > > > > > atomic64_t num_reads; /* failed + successful */ > > > > > atomic64_t num_writes; /* --do-- */ > > > > > - atomic64_t failed_reads; /* should NEVER! happen */ > > > > > + atomic64_t failed_reads; /* can happen when memory is too low */ > > > > > > this grabbed my attention. > > > > "failed_writes; /* can happen when memory is too low */" > > > > theoretically, we can have a misbehaving compression algorithm. so the > > question is -- should we fail write() if compression has failed for any > > other reason, rather than -ENOMEM? alternatively, we can store uncompressed > > user mem, just the same way we do for `badly' compressed buffers, set a > > FAILED_COMPRESSION flag (so we will not leak kernel memory on read() if we > > failed to compress is_partial_io() bv_page), and on read() copy it out as is, > > just as we do for `badly' compessed pages. > > > > so, what do you think? /* I can take a look on it */ > > How often does it happen? > I don't think it's valuable to maintain if it's too rare. > Rather, I'd like to remove the comment on failed_writes. :) > I don't think I've ever observed any errors. and, apparently, lzo is always `return LZO_E_OK'. so let's just drop it. -ss ^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH v2] zram: fix incorrectly stat with failed_reads 2014-08-13 2:01 [PATCH v2] zram: fix incorrectly stat with failed_reads Chao Yu 2014-08-13 8:31 ` Jerome Marchand @ 2014-08-14 0:26 ` Minchan Kim 1 sibling, 0 replies; 8+ messages in thread From: Minchan Kim @ 2014-08-14 0:26 UTC (permalink / raw) To: Chao Yu Cc: ngupta, linux-kernel, 'Jerome Marchand', 'Sergey Senozhatsky', 'Andrew Morton' On Wed, Aug 13, 2014 at 10:01:45AM +0800, Chao Yu wrote: > Since we allocate a temporary buffer in zram_bvec_read to handle partial page > operations in this commit 924bd88d703e53d30f393fac6117f8f1bc79aab6 (Staging: > zram: allow partial page operations), our ->failed_reads value may be incorrect > as we do not increase its value when failed to allocate the temporary buffer. > > Let's fix this issue and correct the annotation of failed_reads. > > v2: clean codes of failed_{reads,writes} stat pointed out by Minchan Kim, and > this cleanup also fix incorrectly stat when fail in zram_decompress_page. > > Signed-off-by: Chao Yu <chao2.yu@samsung.com> Acked-by: Minchan Kim <minchan@kernel.org> Thanks! -- Kind regards, Minchan Kim ^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2014-08-14 12:56 UTC | newest] Thread overview: 8+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2014-08-13 2:01 [PATCH v2] zram: fix incorrectly stat with failed_reads Chao Yu 2014-08-13 8:31 ` Jerome Marchand 2014-08-13 11:32 ` Sergey Senozhatsky 2014-08-13 14:43 ` Sergey Senozhatsky 2014-08-13 14:49 ` Sergey Senozhatsky 2014-08-13 23:02 ` Minchan Kim 2014-08-14 12:54 ` Sergey Senozhatsky 2014-08-14 0:26 ` Minchan Kim
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