| Message ID | 20220408135323.1559401-2-naoya.horiguchi@linux.dev (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/hwpoison: fix race between hugetlb free/demotion and memory_failure_hugetlb() | expand |
On 2022/4/8 21:53, Naoya Horiguchi wrote: > From: Naoya Horiguchi <naoya.horiguchi@nec.com> > > There is a race condition between memory_failure_hugetlb() and hugetlb > free/demotion, which causes setting PageHWPoison flag on the wrong page. > The one simple result is that wrong processes can be killed, but another > (more serious) one is that the actual error is left unhandled, so no one > prevents later access to it, and that might lead to more serious results > like consuming corrupted data. > > Think about the below race window: > > CPU 1 CPU 2 > memory_failure_hugetlb > struct page *head = compound_head(p); > hugetlb page might be freed to > buddy, or even changed to another > compound page. > > get_hwpoison_page -- page is not what we want now... > > The current code first does prechecks roughly and then reconfirms > after taking refcount, but it's found that it makes code overly > complicated, so move the prechecks in a single hugetlb_lock range. > > A newly introduced function, try_memory_failure_hugetlb(), always > takes hugetlb_lock (even for non-hugetlb pages). That can be > improved, but memory_failure() is rare in principle, so should > not be a big problem. > > Fixes: 761ad8d7c7b5 ("mm: hwpoison: introduce memory_failure_hugetlb()") > Reported-by: Mike Kravetz <mike.kravetz@oracle.com> > Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> This patch looks good to me now. Many thanks for your hard work! Looking forward to see your non-huge page version patch. ;) Reviewed-by: Miaohe Lin <linmiaohe@huawei.com> > Cc: stable@vger.kernel.org > --- > ChangeLog v7 -> v8 > - move hwpoison_filter() within page locking. > > ChangeLog v6 -> v7: > - Move lock_page() to try_memory_failure_hugetlb() > (based on bug report from Dan Carpenter) > - Add Fixes: tag and CC to stable. > > ChangeLog v5 -> v6: > - Moved racy precheck operations into hugetlb_lock (based on > Mike's comment). > - rebased onto v5.18-rc1. > - dropped CC to stable. > > ChangeLog v4 -> v5: > - call TestSetPageHWPoison() when page_handle_poison() fails. > - call TestSetPageHWPoison() for unhandlable cases (MF_MSG_UNKNOWN and > MF_MSG_DIFFERENT_PAGE_SIZE). > - Set PageHWPoison on the head page only when the error page is surely > a hugepage, otherwise set the flag on the raw page. > - rebased onto v5.17-rc8-mmotm-2022-03-16-17-42 > > ChangeLog v3 -> v4: > - squash with "mm/memory-failure.c: fix race with changing page > compound again". > - update patch subject and description based on it. > > ChangeLog v2 -> v3: > - rename the patch because page lock is not the primary factor to > solve the reported issue. > - updated description in the same manner. > - call page_handle_poison() instead of __page_handle_poison() for > free hugepage case. > - reorder put_page and unlock_page (thanks to Miaohe Lin) > > ChangeLog v1 -> v2: > - pass subpage to get_hwpoison_huge_page() instead of head page. > - call compound_head() in hugetlb_lock to avoid race with hugetlb > demotion/free. > --- > include/linux/hugetlb.h | 6 ++ > include/linux/mm.h | 8 +++ > mm/hugetlb.c | 10 +++ > mm/memory-failure.c | 145 ++++++++++++++++++++++++++++------------ > 4 files changed, 127 insertions(+), 42 deletions(-) > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index 53c1b6082a4c..ac2a1d758a80 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -169,6 +169,7 @@ long hugetlb_unreserve_pages(struct inode *inode, long start, long end, > long freed); > bool isolate_huge_page(struct page *page, struct list_head *list); > int get_hwpoison_huge_page(struct page *page, bool *hugetlb); > +int get_huge_page_for_hwpoison(unsigned long pfn, int flags); > void putback_active_hugepage(struct page *page); > void move_hugetlb_state(struct page *oldpage, struct page *newpage, int reason); > void free_huge_page(struct page *page); > @@ -378,6 +379,11 @@ static inline int get_hwpoison_huge_page(struct page *page, bool *hugetlb) > return 0; > } > > +static inline int get_huge_page_for_hwpoison(unsigned long pfn, int flags) > +{ > + return 0; > +} > + > static inline void putback_active_hugepage(struct page *page) > { > } > diff --git a/include/linux/mm.h b/include/linux/mm.h > index e34edb775334..9f44254af8ce 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -3197,6 +3197,14 @@ extern int sysctl_memory_failure_recovery; > extern void shake_page(struct page *p); > extern atomic_long_t num_poisoned_pages __read_mostly; > extern int soft_offline_page(unsigned long pfn, int flags); > +#ifdef CONFIG_MEMORY_FAILURE > +extern int __get_huge_page_for_hwpoison(unsigned long pfn, int flags); > +#else > +static inline int __get_huge_page_for_hwpoison(unsigned long pfn, int flags) > +{ > + return 0; > +} > +#endif > > #ifndef arch_memory_failure > static inline int arch_memory_failure(unsigned long pfn, int flags) > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index f8ca7cca3c1a..3fc721789743 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -6785,6 +6785,16 @@ int get_hwpoison_huge_page(struct page *page, bool *hugetlb) > return ret; > } > > +int get_huge_page_for_hwpoison(unsigned long pfn, int flags) > +{ > + int ret; > + > + spin_lock_irq(&hugetlb_lock); > + ret = __get_huge_page_for_hwpoison(pfn, flags); > + spin_unlock_irq(&hugetlb_lock); > + return ret; > +} > + > void putback_active_hugepage(struct page *page) > { > spin_lock_irq(&hugetlb_lock); > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > index dcb6bb9cf731..2020944398c9 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -1498,50 +1498,113 @@ static int try_to_split_thp_page(struct page *page, const char *msg) > return 0; > } > > -static int memory_failure_hugetlb(unsigned long pfn, int flags) > +/* > + * Called from hugetlb code with hugetlb_lock held. > + * > + * Return values: > + * 0 - free hugepage > + * 1 - in-use hugepage > + * 2 - not a hugepage > + * -EBUSY - the hugepage is busy (try to retry) > + * -EHWPOISON - the hugepage is already hwpoisoned > + */ > +int __get_huge_page_for_hwpoison(unsigned long pfn, int flags) > +{ > + struct page *page = pfn_to_page(pfn); > + struct page *head = compound_head(page); > + int ret = 2; /* fallback to normal page handling */ > + bool count_increased = false; > + > + if (!PageHeadHuge(head)) > + goto out; > + > + if (flags & MF_COUNT_INCREASED) { > + ret = 1; > + count_increased = true; > + } else if (HPageFreed(head) || HPageMigratable(head)) { > + ret = get_page_unless_zero(head); > + if (ret) > + count_increased = true; > + } else { > + ret = -EBUSY; > + goto out; > + } > + > + if (TestSetPageHWPoison(head)) { > + ret = -EHWPOISON; > + goto out; > + } > + > + return ret; > +out: > + if (count_increased) > + put_page(head); > + return ret; > +} > + > +#ifdef CONFIG_HUGETLB_PAGE > +/* > + * Taking refcount of hugetlb pages needs extra care about race conditions > + * with basic operations like hugepage allocation/free/demotion. > + * So some of prechecks for hwpoison (pinning, and testing/setting > + * PageHWPoison) should be done in single hugetlb_lock range. > + */ > +static int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb) > { > - struct page *p = pfn_to_page(pfn); > - struct page *head = compound_head(p); > int res; > + struct page *p = pfn_to_page(pfn); > + struct page *head; > unsigned long page_flags; > + bool retry = true; > > - if (TestSetPageHWPoison(head)) { > - pr_err("Memory failure: %#lx: already hardware poisoned\n", > - pfn); > - res = -EHWPOISON; > - if (flags & MF_ACTION_REQUIRED) > + *hugetlb = 1; > +retry: > + res = get_huge_page_for_hwpoison(pfn, flags); > + if (res == 2) { /* fallback to normal page handling */ > + *hugetlb = 0; > + return 0; > + } else if (res == -EHWPOISON) { > + pr_err("Memory failure: %#lx: already hardware poisoned\n", pfn); > + if (flags & MF_ACTION_REQUIRED) { > + head = compound_head(p); > res = kill_accessing_process(current, page_to_pfn(head), flags); > + } > return res; > + } else if (res == -EBUSY) { > + if (retry) { > + retry = false; > + goto retry; > + } > + action_result(pfn, MF_MSG_UNKNOWN, MF_IGNORED); > + return res; > + } > + > + head = compound_head(p); > + lock_page(head); > + > + if (hwpoison_filter(p)) { > + ClearPageHWPoison(head); > + res = -EOPNOTSUPP; > + goto out; > } > > num_poisoned_pages_inc(); > > - if (!(flags & MF_COUNT_INCREASED)) { > - res = get_hwpoison_page(p, flags); > - if (!res) { > - lock_page(head); > - if (hwpoison_filter(p)) { > - if (TestClearPageHWPoison(head)) > - num_poisoned_pages_dec(); > - unlock_page(head); > - return -EOPNOTSUPP; > - } > - unlock_page(head); > - res = MF_FAILED; > - if (__page_handle_poison(p)) { > - page_ref_inc(p); > - res = MF_RECOVERED; > - } > - action_result(pfn, MF_MSG_FREE_HUGE, res); > - return res == MF_RECOVERED ? 0 : -EBUSY; > - } else if (res < 0) { > - action_result(pfn, MF_MSG_UNKNOWN, MF_IGNORED); > - return -EBUSY; > + /* > + * Handling free hugepage. The possible race with hugepage allocation > + * or demotion can be prevented by PageHWPoison flag. > + */ > + if (res == 0) { > + unlock_page(head); > + res = MF_FAILED; > + if (__page_handle_poison(p)) { > + page_ref_inc(p); > + res = MF_RECOVERED; > } > + action_result(pfn, MF_MSG_FREE_HUGE, res); > + return res == MF_RECOVERED ? 0 : -EBUSY; > } > > - lock_page(head); > - > /* > * The page could have changed compound pages due to race window. > * If this happens just bail out. > @@ -1554,14 +1617,6 @@ static int memory_failure_hugetlb(unsigned long pfn, int flags) > > page_flags = head->flags; > > - if (hwpoison_filter(p)) { > - if (TestClearPageHWPoison(head)) > - num_poisoned_pages_dec(); > - put_page(p); > - res = -EOPNOTSUPP; > - goto out; > - } > - > /* > * TODO: hwpoison for pud-sized hugetlb doesn't work right now, so > * simply disable it. In order to make it work properly, we need > @@ -1588,6 +1643,12 @@ static int memory_failure_hugetlb(unsigned long pfn, int flags) > unlock_page(head); > return res; > } > +#else > +static inline int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb) > +{ > + return 0; > +} > +#endif > > static int memory_failure_dev_pagemap(unsigned long pfn, int flags, > struct dev_pagemap *pgmap) > @@ -1712,6 +1773,7 @@ int memory_failure(unsigned long pfn, int flags) > int res = 0; > unsigned long page_flags; > bool retry = true; > + int hugetlb = 0; > > if (!sysctl_memory_failure_recovery) > panic("Memory failure on page %lx", pfn); > @@ -1739,10 +1801,9 @@ int memory_failure(unsigned long pfn, int flags) > } > > try_again: > - if (PageHuge(p)) { > - res = memory_failure_hugetlb(pfn, flags); > + res = try_memory_failure_hugetlb(pfn, flags, &hugetlb); > + if (hugetlb) > goto unlock_mutex; > - } > > if (TestSetPageHWPoison(p)) { > pr_err("Memory failure: %#lx: already hardware poisoned\n", >
On 4/8/22 06:53, Naoya Horiguchi wrote: > From: Naoya Horiguchi <naoya.horiguchi@nec.com> > > There is a race condition between memory_failure_hugetlb() and hugetlb > free/demotion, which causes setting PageHWPoison flag on the wrong page. > The one simple result is that wrong processes can be killed, but another > (more serious) one is that the actual error is left unhandled, so no one > prevents later access to it, and that might lead to more serious results > like consuming corrupted data. > > Think about the below race window: > > CPU 1 CPU 2 > memory_failure_hugetlb > struct page *head = compound_head(p); > hugetlb page might be freed to > buddy, or even changed to another > compound page. > > get_hwpoison_page -- page is not what we want now... > > The current code first does prechecks roughly and then reconfirms > after taking refcount, but it's found that it makes code overly > complicated, so move the prechecks in a single hugetlb_lock range. > > A newly introduced function, try_memory_failure_hugetlb(), always > takes hugetlb_lock (even for non-hugetlb pages). That can be > improved, but memory_failure() is rare in principle, so should > not be a big problem. Thanks! I think this approach is the safest and makes the code easier to understand. > > Fixes: 761ad8d7c7b5 ("mm: hwpoison: introduce memory_failure_hugetlb()") > Reported-by: Mike Kravetz <mike.kravetz@oracle.com> > Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com> > Cc: stable@vger.kernel.org > --- ... > --- > include/linux/hugetlb.h | 6 ++ > include/linux/mm.h | 8 +++ > mm/hugetlb.c | 10 +++ > mm/memory-failure.c | 145 ++++++++++++++++++++++++++++------------ > 4 files changed, 127 insertions(+), 42 deletions(-) > > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index 53c1b6082a4c..ac2a1d758a80 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -169,6 +169,7 @@ long hugetlb_unreserve_pages(struct inode *inode, long start, long end, > long freed); > bool isolate_huge_page(struct page *page, struct list_head *list); > int get_hwpoison_huge_page(struct page *page, bool *hugetlb); > +int get_huge_page_for_hwpoison(unsigned long pfn, int flags); > void putback_active_hugepage(struct page *page); > void move_hugetlb_state(struct page *oldpage, struct page *newpage, int reason); > void free_huge_page(struct page *page); > @@ -378,6 +379,11 @@ static inline int get_hwpoison_huge_page(struct page *page, bool *hugetlb) > return 0; > } > > +static inline int get_huge_page_for_hwpoison(unsigned long pfn, int flags) > +{ > + return 0; > +} > + > static inline void putback_active_hugepage(struct page *page) > { > } > diff --git a/include/linux/mm.h b/include/linux/mm.h > index e34edb775334..9f44254af8ce 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -3197,6 +3197,14 @@ extern int sysctl_memory_failure_recovery; > extern void shake_page(struct page *p); > extern atomic_long_t num_poisoned_pages __read_mostly; > extern int soft_offline_page(unsigned long pfn, int flags); > +#ifdef CONFIG_MEMORY_FAILURE > +extern int __get_huge_page_for_hwpoison(unsigned long pfn, int flags); > +#else > +static inline int __get_huge_page_for_hwpoison(unsigned long pfn, int flags) > +{ > + return 0; > +} > +#endif > > #ifndef arch_memory_failure > static inline int arch_memory_failure(unsigned long pfn, int flags) > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index f8ca7cca3c1a..3fc721789743 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -6785,6 +6785,16 @@ int get_hwpoison_huge_page(struct page *page, bool *hugetlb) > return ret; > } > > +int get_huge_page_for_hwpoison(unsigned long pfn, int flags) > +{ > + int ret; > + > + spin_lock_irq(&hugetlb_lock); > + ret = __get_huge_page_for_hwpoison(pfn, flags); > + spin_unlock_irq(&hugetlb_lock); > + return ret; > +} > + > void putback_active_hugepage(struct page *page) > { > spin_lock_irq(&hugetlb_lock); > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > index dcb6bb9cf731..2020944398c9 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -1498,50 +1498,113 @@ static int try_to_split_thp_page(struct page *page, const char *msg) > return 0; > } > > -static int memory_failure_hugetlb(unsigned long pfn, int flags) > +/* > + * Called from hugetlb code with hugetlb_lock held. > + * > + * Return values: > + * 0 - free hugepage > + * 1 - in-use hugepage > + * 2 - not a hugepage > + * -EBUSY - the hugepage is busy (try to retry) > + * -EHWPOISON - the hugepage is already hwpoisoned > + */ > +int __get_huge_page_for_hwpoison(unsigned long pfn, int flags) > +{ > + struct page *page = pfn_to_page(pfn); > + struct page *head = compound_head(page); > + int ret = 2; /* fallback to normal page handling */ > + bool count_increased = false; > + > + if (!PageHeadHuge(head)) > + goto out; > + > + if (flags & MF_COUNT_INCREASED) { > + ret = 1; > + count_increased = true; > + } else if (HPageFreed(head) || HPageMigratable(head)) { > + ret = get_page_unless_zero(head); > + if (ret) > + count_increased = true; The above code works as designed, but may be a bit confusing. If HPageFreed() we KNOW ref count is zero, so no need to even call get_page_unless_zero() as it will always return false in this case. It might be more clear if written as separate else if statements such as: } else if (HPageFreed(head)) { ret = 0; } else if (HPageMigratable(head)) { ret = get_page_unless_zero(head); if (ret) count_increased = true; Not insisting this be changed. Just easier to understand IMO. Again, thanks for your work on this! Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
On 2022/4/15 1:56, Mike Kravetz wrote: > On 4/8/22 06:53, Naoya Horiguchi wrote: >> From: Naoya Horiguchi <naoya.horiguchi@nec.com> >> >> There is a race condition between memory_failure_hugetlb() and hugetlb >> free/demotion, which causes setting PageHWPoison flag on the wrong page. >> The one simple result is that wrong processes can be killed, but another >> (more serious) one is that the actual error is left unhandled, so no one >> prevents later access to it, and that might lead to more serious results >> like consuming corrupted data. >> >> Think about the below race window: >> >> CPU 1 CPU 2 >> memory_failure_hugetlb >> struct page *head = compound_head(p); >> hugetlb page might be freed to >> buddy, or even changed to another >> compound page. >> >> get_hwpoison_page -- page is not what we want now... >> >> The current code first does prechecks roughly and then reconfirms >> after taking refcount, but it's found that it makes code overly >> complicated, so move the prechecks in a single hugetlb_lock range. >> >> A newly introduced function, try_memory_failure_hugetlb(), always >> takes hugetlb_lock (even for non-hugetlb pages). That can be >> improved, but memory_failure() is rare in principle, so should >> not be a big problem. ... > > The above code works as designed, but may be a bit confusing. If HPageFreed() > we KNOW ref count is zero, so no need to even call get_page_unless_zero() as > it will always return false in this case. It might be more clear if written > as separate else if statements such as: > > } else if (HPageFreed(head)) { > ret = 0; > } else if (HPageMigratable(head)) { > ret = get_page_unless_zero(head); > if (ret) > count_increased = true; > This code here is consistent with the logic in get_hwpoison_huge_page. If change is required, they might need to be changed together. BTW: They look a bit confusing for me at first but I get used to it later. ;) Thanks! > Not insisting this be changed. Just easier to understand IMO. > > Again, thanks for your work on this! > > Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> >
On Fri, Apr 15, 2022 at 09:55:14AM +0800, Miaohe Lin wrote: > On 2022/4/15 1:56, Mike Kravetz wrote: > > On 4/8/22 06:53, Naoya Horiguchi wrote: > >> From: Naoya Horiguchi <naoya.horiguchi@nec.com> > >> > >> There is a race condition between memory_failure_hugetlb() and hugetlb > >> free/demotion, which causes setting PageHWPoison flag on the wrong page. > >> The one simple result is that wrong processes can be killed, but another > >> (more serious) one is that the actual error is left unhandled, so no one > >> prevents later access to it, and that might lead to more serious results > >> like consuming corrupted data. > >> > >> Think about the below race window: > >> > >> CPU 1 CPU 2 > >> memory_failure_hugetlb > >> struct page *head = compound_head(p); > >> hugetlb page might be freed to > >> buddy, or even changed to another > >> compound page. > >> > >> get_hwpoison_page -- page is not what we want now... > >> > >> The current code first does prechecks roughly and then reconfirms > >> after taking refcount, but it's found that it makes code overly > >> complicated, so move the prechecks in a single hugetlb_lock range. > >> > >> A newly introduced function, try_memory_failure_hugetlb(), always > >> takes hugetlb_lock (even for non-hugetlb pages). That can be > >> improved, but memory_failure() is rare in principle, so should > >> not be a big problem. > ... > > > > The above code works as designed, but may be a bit confusing. If HPageFreed() > > we KNOW ref count is zero, so no need to even call get_page_unless_zero() as > > it will always return false in this case. It might be more clear if written > > as separate else if statements such as: > > > > } else if (HPageFreed(head)) { > > ret = 0; > > } else if (HPageMigratable(head)) { > > ret = get_page_unless_zero(head); > > if (ret) > > count_increased = true; > > > > This code here is consistent with the logic in get_hwpoison_huge_page. If change is required, > they might need to be changed together. > > BTW: They look a bit confusing for me at first but I get used to it later. ;) Thank you for comments, Mike, Miaohe. Patch 1/3 is to stable, so I'll submit a separate cleanup patch for these changes. > > Thanks! > > > Not insisting this be changed. Just easier to understand IMO. > > > > Again, thanks for your work on this! > > > > Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Thank you! - Naoya Horiguchi
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 53c1b6082a4c..ac2a1d758a80 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -169,6 +169,7 @@ long hugetlb_unreserve_pages(struct inode *inode, long start, long end, long freed); bool isolate_huge_page(struct page *page, struct list_head *list); int get_hwpoison_huge_page(struct page *page, bool *hugetlb); +int get_huge_page_for_hwpoison(unsigned long pfn, int flags); void putback_active_hugepage(struct page *page); void move_hugetlb_state(struct page *oldpage, struct page *newpage, int reason); void free_huge_page(struct page *page); @@ -378,6 +379,11 @@ static inline int get_hwpoison_huge_page(struct page *page, bool *hugetlb) return 0; } +static inline int get_huge_page_for_hwpoison(unsigned long pfn, int flags) +{ + return 0; +} + static inline void putback_active_hugepage(struct page *page) { } diff --git a/include/linux/mm.h b/include/linux/mm.h index e34edb775334..9f44254af8ce 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3197,6 +3197,14 @@ extern int sysctl_memory_failure_recovery; extern void shake_page(struct page *p); extern atomic_long_t num_poisoned_pages __read_mostly; extern int soft_offline_page(unsigned long pfn, int flags); +#ifdef CONFIG_MEMORY_FAILURE +extern int __get_huge_page_for_hwpoison(unsigned long pfn, int flags); +#else +static inline int __get_huge_page_for_hwpoison(unsigned long pfn, int flags) +{ + return 0; +} +#endif #ifndef arch_memory_failure static inline int arch_memory_failure(unsigned long pfn, int flags) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index f8ca7cca3c1a..3fc721789743 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6785,6 +6785,16 @@ int get_hwpoison_huge_page(struct page *page, bool *hugetlb) return ret; } +int get_huge_page_for_hwpoison(unsigned long pfn, int flags) +{ + int ret; + + spin_lock_irq(&hugetlb_lock); + ret = __get_huge_page_for_hwpoison(pfn, flags); + spin_unlock_irq(&hugetlb_lock); + return ret; +} + void putback_active_hugepage(struct page *page) { spin_lock_irq(&hugetlb_lock); diff --git a/mm/memory-failure.c b/mm/memory-failure.c index dcb6bb9cf731..2020944398c9 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1498,50 +1498,113 @@ static int try_to_split_thp_page(struct page *page, const char *msg) return 0; } -static int memory_failure_hugetlb(unsigned long pfn, int flags) +/* + * Called from hugetlb code with hugetlb_lock held. + * + * Return values: + * 0 - free hugepage + * 1 - in-use hugepage + * 2 - not a hugepage + * -EBUSY - the hugepage is busy (try to retry) + * -EHWPOISON - the hugepage is already hwpoisoned + */ +int __get_huge_page_for_hwpoison(unsigned long pfn, int flags) +{ + struct page *page = pfn_to_page(pfn); + struct page *head = compound_head(page); + int ret = 2; /* fallback to normal page handling */ + bool count_increased = false; + + if (!PageHeadHuge(head)) + goto out; + + if (flags & MF_COUNT_INCREASED) { + ret = 1; + count_increased = true; + } else if (HPageFreed(head) || HPageMigratable(head)) { + ret = get_page_unless_zero(head); + if (ret) + count_increased = true; + } else { + ret = -EBUSY; + goto out; + } + + if (TestSetPageHWPoison(head)) { + ret = -EHWPOISON; + goto out; + } + + return ret; +out: + if (count_increased) + put_page(head); + return ret; +} + +#ifdef CONFIG_HUGETLB_PAGE +/* + * Taking refcount of hugetlb pages needs extra care about race conditions + * with basic operations like hugepage allocation/free/demotion. + * So some of prechecks for hwpoison (pinning, and testing/setting + * PageHWPoison) should be done in single hugetlb_lock range. + */ +static int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb) { - struct page *p = pfn_to_page(pfn); - struct page *head = compound_head(p); int res; + struct page *p = pfn_to_page(pfn); + struct page *head; unsigned long page_flags; + bool retry = true; - if (TestSetPageHWPoison(head)) { - pr_err("Memory failure: %#lx: already hardware poisoned\n", - pfn); - res = -EHWPOISON; - if (flags & MF_ACTION_REQUIRED) + *hugetlb = 1; +retry: + res = get_huge_page_for_hwpoison(pfn, flags); + if (res == 2) { /* fallback to normal page handling */ + *hugetlb = 0; + return 0; + } else if (res == -EHWPOISON) { + pr_err("Memory failure: %#lx: already hardware poisoned\n", pfn); + if (flags & MF_ACTION_REQUIRED) { + head = compound_head(p); res = kill_accessing_process(current, page_to_pfn(head), flags); + } return res; + } else if (res == -EBUSY) { + if (retry) { + retry = false; + goto retry; + } + action_result(pfn, MF_MSG_UNKNOWN, MF_IGNORED); + return res; + } + + head = compound_head(p); + lock_page(head); + + if (hwpoison_filter(p)) { + ClearPageHWPoison(head); + res = -EOPNOTSUPP; + goto out; } num_poisoned_pages_inc(); - if (!(flags & MF_COUNT_INCREASED)) { - res = get_hwpoison_page(p, flags); - if (!res) { - lock_page(head); - if (hwpoison_filter(p)) { - if (TestClearPageHWPoison(head)) - num_poisoned_pages_dec(); - unlock_page(head); - return -EOPNOTSUPP; - } - unlock_page(head); - res = MF_FAILED; - if (__page_handle_poison(p)) { - page_ref_inc(p); - res = MF_RECOVERED; - } - action_result(pfn, MF_MSG_FREE_HUGE, res); - return res == MF_RECOVERED ? 0 : -EBUSY; - } else if (res < 0) { - action_result(pfn, MF_MSG_UNKNOWN, MF_IGNORED); - return -EBUSY; + /* + * Handling free hugepage. The possible race with hugepage allocation + * or demotion can be prevented by PageHWPoison flag. + */ + if (res == 0) { + unlock_page(head); + res = MF_FAILED; + if (__page_handle_poison(p)) { + page_ref_inc(p); + res = MF_RECOVERED; } + action_result(pfn, MF_MSG_FREE_HUGE, res); + return res == MF_RECOVERED ? 0 : -EBUSY; } - lock_page(head); - /* * The page could have changed compound pages due to race window. * If this happens just bail out. @@ -1554,14 +1617,6 @@ static int memory_failure_hugetlb(unsigned long pfn, int flags) page_flags = head->flags; - if (hwpoison_filter(p)) { - if (TestClearPageHWPoison(head)) - num_poisoned_pages_dec(); - put_page(p); - res = -EOPNOTSUPP; - goto out; - } - /* * TODO: hwpoison for pud-sized hugetlb doesn't work right now, so * simply disable it. In order to make it work properly, we need @@ -1588,6 +1643,12 @@ static int memory_failure_hugetlb(unsigned long pfn, int flags) unlock_page(head); return res; } +#else +static inline int try_memory_failure_hugetlb(unsigned long pfn, int flags, int *hugetlb) +{ + return 0; +} +#endif static int memory_failure_dev_pagemap(unsigned long pfn, int flags, struct dev_pagemap *pgmap) @@ -1712,6 +1773,7 @@ int memory_failure(unsigned long pfn, int flags) int res = 0; unsigned long page_flags; bool retry = true; + int hugetlb = 0; if (!sysctl_memory_failure_recovery) panic("Memory failure on page %lx", pfn); @@ -1739,10 +1801,9 @@ int memory_failure(unsigned long pfn, int flags) } try_again: - if (PageHuge(p)) { - res = memory_failure_hugetlb(pfn, flags); + res = try_memory_failure_hugetlb(pfn, flags, &hugetlb); + if (hugetlb) goto unlock_mutex; - } if (TestSetPageHWPoison(p)) { pr_err("Memory failure: %#lx: already hardware poisoned\n",