* [PATCH] mm: frontswap: invalidate expired data on a dup-store failure @ 2014-11-18 8:51 Weijie Yang 2014-11-18 21:41 ` Andrew Morton 2014-11-18 22:29 ` Seth Jennings 0 siblings, 2 replies; 5+ messages in thread From: Weijie Yang @ 2014-11-18 8:51 UTC (permalink / raw) To: konrad.wilk Cc: 'Andrew Morton', 'Seth Jennings', 'Dan Streetman', 'Minchan Kim', 'Bob Liu', xfishcoder, 'Weijie Yang', linux-mm, linux-kernel If a frontswap dup-store failed, it should invalidate the expired page in the backend, or it could trigger some data corruption issue. Such as: 1. use zswap as the frontswap backend with writeback feature 2. store a swap page(version_1) to entry A, success 3. dup-store a newer page(version_2) to the same entry A, fail 4. use __swap_writepage() write version_2 page to swapfile, success 5. zswap do shrink, writeback version_1 page to swapfile 6. version_2 page is overwrited by version_1, data corrupt. This patch fixes this issue by invalidating expired data immediately when meet a dup-store failure. Signed-off-by: Weijie Yang <weijie.yang@samsung.com> --- mm/frontswap.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-) diff --git a/mm/frontswap.c b/mm/frontswap.c index c30eec5..f2a3571 100644 --- a/mm/frontswap.c +++ b/mm/frontswap.c @@ -244,8 +244,10 @@ int __frontswap_store(struct page *page) the (older) page from frontswap */ inc_frontswap_failed_stores(); - if (dup) + if (dup) { __frontswap_clear(sis, offset); + frontswap_ops->invalidate_page(type, offset); + } } if (frontswap_writethrough_enabled) /* report failure so swap also writes to swap device */ -- 1.7.0.4 ^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] mm: frontswap: invalidate expired data on a dup-store failure 2014-11-18 8:51 [PATCH] mm: frontswap: invalidate expired data on a dup-store failure Weijie Yang @ 2014-11-18 21:41 ` Andrew Morton 2014-11-18 22:29 ` Seth Jennings 1 sibling, 0 replies; 5+ messages in thread From: Andrew Morton @ 2014-11-18 21:41 UTC (permalink / raw) To: Weijie Yang Cc: konrad.wilk, 'Seth Jennings', 'Dan Streetman', 'Minchan Kim', 'Bob Liu', xfishcoder, 'Weijie Yang', linux-mm, linux-kernel On Tue, 18 Nov 2014 16:51:36 +0800 Weijie Yang <weijie.yang@samsung.com> wrote: > If a frontswap dup-store failed, it should invalidate the expired page > in the backend, or it could trigger some data corruption issue. > Such as: > 1. use zswap as the frontswap backend with writeback feature > 2. store a swap page(version_1) to entry A, success > 3. dup-store a newer page(version_2) to the same entry A, fail > 4. use __swap_writepage() write version_2 page to swapfile, success > 5. zswap do shrink, writeback version_1 page to swapfile > 6. version_2 page is overwrited by version_1, data corrupt. > > This patch fixes this issue by invalidating expired data immediately > when meet a dup-store failure. > > ... > > --- a/mm/frontswap.c > +++ b/mm/frontswap.c > @@ -244,8 +244,10 @@ int __frontswap_store(struct page *page) > the (older) page from frontswap > */ > inc_frontswap_failed_stores(); > - if (dup) > + if (dup) { > __frontswap_clear(sis, offset); > + frontswap_ops->invalidate_page(type, offset); > + } > } > if (frontswap_writethrough_enabled) > /* report failure so swap also writes to swap device */ I tagged this for backporting into -stable kernels. Please shout at me if you think that was inappropriate. ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] mm: frontswap: invalidate expired data on a dup-store failure 2014-11-18 8:51 [PATCH] mm: frontswap: invalidate expired data on a dup-store failure Weijie Yang 2014-11-18 21:41 ` Andrew Morton @ 2014-11-18 22:29 ` Seth Jennings 2014-11-19 13:06 ` Weijie Yang 1 sibling, 1 reply; 5+ messages in thread From: Seth Jennings @ 2014-11-18 22:29 UTC (permalink / raw) To: Weijie Yang Cc: konrad.wilk, 'Andrew Morton', 'Dan Streetman', 'Minchan Kim', 'Bob Liu', xfishcoder, 'Weijie Yang', linux-mm, linux-kernel On Tue, Nov 18, 2014 at 04:51:36PM +0800, Weijie Yang wrote: > If a frontswap dup-store failed, it should invalidate the expired page > in the backend, or it could trigger some data corruption issue. > Such as: > 1. use zswap as the frontswap backend with writeback feature > 2. store a swap page(version_1) to entry A, success > 3. dup-store a newer page(version_2) to the same entry A, fail > 4. use __swap_writepage() write version_2 page to swapfile, success > 5. zswap do shrink, writeback version_1 page to swapfile > 6. version_2 page is overwrited by version_1, data corrupt. Good catch! > > This patch fixes this issue by invalidating expired data immediately > when meet a dup-store failure. > > Signed-off-by: Weijie Yang <weijie.yang@samsung.com> > --- > mm/frontswap.c | 4 +++- > 1 files changed, 3 insertions(+), 1 deletions(-) > > diff --git a/mm/frontswap.c b/mm/frontswap.c > index c30eec5..f2a3571 100644 > --- a/mm/frontswap.c > +++ b/mm/frontswap.c > @@ -244,8 +244,10 @@ int __frontswap_store(struct page *page) > the (older) page from frontswap > */ > inc_frontswap_failed_stores(); > - if (dup) > + if (dup) { > __frontswap_clear(sis, offset); > + frontswap_ops->invalidate_page(type, offset); Looking at __frontswap_invalidate_page(), should we do inc_frontswap_invalidates() too? If so, maybe we should just call __frontswap_invalidate_page(). Thanks, Seth > + } > } > if (frontswap_writethrough_enabled) > /* report failure so swap also writes to swap device */ > -- > 1.7.0.4 > > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@kvack.org. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] mm: frontswap: invalidate expired data on a dup-store failure 2014-11-18 22:29 ` Seth Jennings @ 2014-11-19 13:06 ` Weijie Yang 2014-11-19 15:43 ` Seth Jennings 0 siblings, 1 reply; 5+ messages in thread From: Weijie Yang @ 2014-11-19 13:06 UTC (permalink / raw) To: Seth Jennings Cc: Weijie Yang, Konrad Rzeszutek Wilk, Andrew Morton, Dan Streetman, Minchan Kim, Bob Liu, 李常坤, Linux-MM, Linux-Kernel On Wed, Nov 19, 2014 at 6:29 AM, Seth Jennings <sjennings@variantweb.net> wrote: > On Tue, Nov 18, 2014 at 04:51:36PM +0800, Weijie Yang wrote: >> If a frontswap dup-store failed, it should invalidate the expired page >> in the backend, or it could trigger some data corruption issue. >> Such as: >> 1. use zswap as the frontswap backend with writeback feature >> 2. store a swap page(version_1) to entry A, success >> 3. dup-store a newer page(version_2) to the same entry A, fail >> 4. use __swap_writepage() write version_2 page to swapfile, success >> 5. zswap do shrink, writeback version_1 page to swapfile >> 6. version_2 page is overwrited by version_1, data corrupt. > > Good catch! > >> >> This patch fixes this issue by invalidating expired data immediately >> when meet a dup-store failure. >> >> Signed-off-by: Weijie Yang <weijie.yang@samsung.com> >> --- >> mm/frontswap.c | 4 +++- >> 1 files changed, 3 insertions(+), 1 deletions(-) >> >> diff --git a/mm/frontswap.c b/mm/frontswap.c >> index c30eec5..f2a3571 100644 >> --- a/mm/frontswap.c >> +++ b/mm/frontswap.c >> @@ -244,8 +244,10 @@ int __frontswap_store(struct page *page) >> the (older) page from frontswap >> */ >> inc_frontswap_failed_stores(); >> - if (dup) >> + if (dup) { >> __frontswap_clear(sis, offset); >> + frontswap_ops->invalidate_page(type, offset); > > Looking at __frontswap_invalidate_page(), should we do > inc_frontswap_invalidates() too? If so, maybe we should just call > __frontswap_invalidate_page(). The frontswap_invalidate_page() is for swap_entry_free, while here is an inner ops for dup-store, so I think there is no need for inc_frontswap_invalidates(). > Thanks, > Seth > >> + } >> } >> if (frontswap_writethrough_enabled) >> /* report failure so swap also writes to swap device */ >> -- >> 1.7.0.4 >> >> >> -- >> To unsubscribe, send a message with 'unsubscribe linux-mm' in >> the body to majordomo@kvack.org. For more info on Linux MM, >> see: http://www.linux-mm.org/ . >> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] mm: frontswap: invalidate expired data on a dup-store failure 2014-11-19 13:06 ` Weijie Yang @ 2014-11-19 15:43 ` Seth Jennings 0 siblings, 0 replies; 5+ messages in thread From: Seth Jennings @ 2014-11-19 15:43 UTC (permalink / raw) To: Weijie Yang Cc: Weijie Yang, Konrad Rzeszutek Wilk, Andrew Morton, Dan Streetman, Minchan Kim, Bob Liu, 李常坤, Linux-MM, Linux-Kernel On Wed, Nov 19, 2014 at 09:06:41PM +0800, Weijie Yang wrote: > On Wed, Nov 19, 2014 at 6:29 AM, Seth Jennings <sjennings@variantweb.net> wrote: > > On Tue, Nov 18, 2014 at 04:51:36PM +0800, Weijie Yang wrote: > >> If a frontswap dup-store failed, it should invalidate the expired page > >> in the backend, or it could trigger some data corruption issue. > >> Such as: > >> 1. use zswap as the frontswap backend with writeback feature > >> 2. store a swap page(version_1) to entry A, success > >> 3. dup-store a newer page(version_2) to the same entry A, fail > >> 4. use __swap_writepage() write version_2 page to swapfile, success > >> 5. zswap do shrink, writeback version_1 page to swapfile > >> 6. version_2 page is overwrited by version_1, data corrupt. > > > > Good catch! > > > >> > >> This patch fixes this issue by invalidating expired data immediately > >> when meet a dup-store failure. > >> > >> Signed-off-by: Weijie Yang <weijie.yang@samsung.com> > >> --- > >> mm/frontswap.c | 4 +++- > >> 1 files changed, 3 insertions(+), 1 deletions(-) > >> > >> diff --git a/mm/frontswap.c b/mm/frontswap.c > >> index c30eec5..f2a3571 100644 > >> --- a/mm/frontswap.c > >> +++ b/mm/frontswap.c > >> @@ -244,8 +244,10 @@ int __frontswap_store(struct page *page) > >> the (older) page from frontswap > >> */ > >> inc_frontswap_failed_stores(); > >> - if (dup) > >> + if (dup) { > >> __frontswap_clear(sis, offset); > >> + frontswap_ops->invalidate_page(type, offset); > > > > Looking at __frontswap_invalidate_page(), should we do > > inc_frontswap_invalidates() too? If so, maybe we should just call > > __frontswap_invalidate_page(). > > The frontswap_invalidate_page() is for swap_entry_free, while here > is an inner ops for dup-store, so I think there is no need for > inc_frontswap_invalidates(). In my mind, I agree we shouldn't call __frontswap_invalidate_page(), just to keep things separated. Andrew has already pulled it in and it isn't a big deal. Just a statistics thing on a rare situation (dup) counted along with lots of frequent situations (normal invalidate). Which makes me think we make want to count dup-invalidates as a separate stat. But that would be a separate patch too :) Thanks, Seth > > > Thanks, > > Seth > > > >> + } > >> } > >> if (frontswap_writethrough_enabled) > >> /* report failure so swap also writes to swap device */ > >> -- > >> 1.7.0.4 > >> > >> > >> -- > >> To unsubscribe, send a message with 'unsubscribe linux-mm' in > >> the body to majordomo@kvack.org. For more info on Linux MM, > >> see: http://www.linux-mm.org/ . > >> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a> ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2014-11-19 15:43 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2014-11-18 8:51 [PATCH] mm: frontswap: invalidate expired data on a dup-store failure Weijie Yang 2014-11-18 21:41 ` Andrew Morton 2014-11-18 22:29 ` Seth Jennings 2014-11-19 13:06 ` Weijie Yang 2014-11-19 15:43 ` Seth Jennings
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