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authorLinus Torvalds <torvalds@linux-foundation.org>2018-08-25 18:43:59 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-08-25 18:43:59 -0700
commit2923b27e54242acf27fd16b299e102117c82f52f (patch)
tree86b3e27575814dab74307a7928bf579455b70e24 /fs
parent828bf6e904eb8fc8969333568802689fbbf07a40 (diff)
parentc953cc987ab87d180e1d5de2f1c217abe33aac77 (diff)
download96b-common-2923b27e54242acf27fd16b299e102117c82f52f.tar.gz
Merge tag 'libnvdimm-for-4.19_dax-memory-failure' of gitolite.kernel.org:pub/scm/linux/kernel/git/nvdimm/nvdimm
Pull libnvdimm memory-failure update from Dave Jiang: "As it stands, memory_failure() gets thoroughly confused by dev_pagemap backed mappings. The recovery code has specific enabling for several possible page states and needs new enabling to handle poison in dax mappings. In order to support reliable reverse mapping of user space addresses: 1/ Add new locking in the memory_failure() rmap path to prevent races that would typically be handled by the page lock. 2/ Since dev_pagemap pages are hidden from the page allocator and the "compound page" accounting machinery, add a mechanism to determine the size of the mapping that encompasses a given poisoned pfn. 3/ Given pmem errors can be repaired, change the speculatively accessed poison protection, mce_unmap_kpfn(), to be reversible and otherwise allow ongoing access from the kernel. A side effect of this enabling is that MADV_HWPOISON becomes usable for dax mappings, however the primary motivation is to allow the system to survive userspace consumption of hardware-poison via dax. Specifically the current behavior is: mce: Uncorrected hardware memory error in user-access at af34214200 {1}[Hardware Error]: It has been corrected by h/w and requires no further action mce: [Hardware Error]: Machine check events logged {1}[Hardware Error]: event severity: corrected Memory failure: 0xaf34214: reserved kernel page still referenced by 1 users [..] Memory failure: 0xaf34214: recovery action for reserved kernel page: Failed mce: Memory error not recovered <reboot> ...and with these changes: Injecting memory failure for pfn 0x20cb00 at process virtual address 0x7f763dd00000 Memory failure: 0x20cb00: Killing dax-pmd:5421 due to hardware memory corruption Memory failure: 0x20cb00: recovery action for dax page: Recovered Given all the cross dependencies I propose taking this through nvdimm.git with acks from Naoya, x86/core, x86/RAS, and of course dax folks" * tag 'libnvdimm-for-4.19_dax-memory-failure' of gitolite.kernel.org:pub/scm/linux/kernel/git/nvdimm/nvdimm: libnvdimm, pmem: Restore page attributes when clearing errors x86/memory_failure: Introduce {set, clear}_mce_nospec() x86/mm/pat: Prepare {reserve, free}_memtype() for "decoy" addresses mm, memory_failure: Teach memory_failure() about dev_pagemap pages filesystem-dax: Introduce dax_lock_mapping_entry() mm, memory_failure: Collect mapping size in collect_procs() mm, madvise_inject_error: Let memory_failure() optionally take a page reference mm, dev_pagemap: Do not clear ->mapping on final put mm, madvise_inject_error: Disable MADV_SOFT_OFFLINE for ZONE_DEVICE pages filesystem-dax: Set page->index device-dax: Set page->index device-dax: Enable page_mapping() device-dax: Convert to vmf_insert_mixed and vm_fault_t
Diffstat (limited to 'fs')
-rw-r--r--fs/dax.c125
1 files changed, 116 insertions, 9 deletions
diff --git a/fs/dax.c b/fs/dax.c
index f76724139f80..f32d7125ad0f 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -226,8 +226,8 @@ static inline void *unlock_slot(struct address_space *mapping, void **slot)
*
* Must be called with the i_pages lock held.
*/
-static void *get_unlocked_mapping_entry(struct address_space *mapping,
- pgoff_t index, void ***slotp)
+static void *__get_unlocked_mapping_entry(struct address_space *mapping,
+ pgoff_t index, void ***slotp, bool (*wait_fn)(void))
{
void *entry, **slot;
struct wait_exceptional_entry_queue ewait;
@@ -237,6 +237,8 @@ static void *get_unlocked_mapping_entry(struct address_space *mapping,
ewait.wait.func = wake_exceptional_entry_func;
for (;;) {
+ bool revalidate;
+
entry = __radix_tree_lookup(&mapping->i_pages, index, NULL,
&slot);
if (!entry ||
@@ -251,14 +253,31 @@ static void *get_unlocked_mapping_entry(struct address_space *mapping,
prepare_to_wait_exclusive(wq, &ewait.wait,
TASK_UNINTERRUPTIBLE);
xa_unlock_irq(&mapping->i_pages);
- schedule();
+ revalidate = wait_fn();
finish_wait(wq, &ewait.wait);
xa_lock_irq(&mapping->i_pages);
+ if (revalidate)
+ return ERR_PTR(-EAGAIN);
}
}
-static void dax_unlock_mapping_entry(struct address_space *mapping,
- pgoff_t index)
+static bool entry_wait(void)
+{
+ schedule();
+ /*
+ * Never return an ERR_PTR() from
+ * __get_unlocked_mapping_entry(), just keep looping.
+ */
+ return false;
+}
+
+static void *get_unlocked_mapping_entry(struct address_space *mapping,
+ pgoff_t index, void ***slotp)
+{
+ return __get_unlocked_mapping_entry(mapping, index, slotp, entry_wait);
+}
+
+static void unlock_mapping_entry(struct address_space *mapping, pgoff_t index)
{
void *entry, **slot;
@@ -277,7 +296,7 @@ static void dax_unlock_mapping_entry(struct address_space *mapping,
static void put_locked_mapping_entry(struct address_space *mapping,
pgoff_t index)
{
- dax_unlock_mapping_entry(mapping, index);
+ unlock_mapping_entry(mapping, index);
}
/*
@@ -319,18 +338,27 @@ static unsigned long dax_radix_end_pfn(void *entry)
for (pfn = dax_radix_pfn(entry); \
pfn < dax_radix_end_pfn(entry); pfn++)
-static void dax_associate_entry(void *entry, struct address_space *mapping)
+/*
+ * TODO: for reflink+dax we need a way to associate a single page with
+ * multiple address_space instances at different linear_page_index()
+ * offsets.
+ */
+static void dax_associate_entry(void *entry, struct address_space *mapping,
+ struct vm_area_struct *vma, unsigned long address)
{
- unsigned long pfn;
+ unsigned long size = dax_entry_size(entry), pfn, index;
+ int i = 0;
if (IS_ENABLED(CONFIG_FS_DAX_LIMITED))
return;
+ index = linear_page_index(vma, address & ~(size - 1));
for_each_mapped_pfn(entry, pfn) {
struct page *page = pfn_to_page(pfn);
WARN_ON_ONCE(page->mapping);
page->mapping = mapping;
+ page->index = index + i++;
}
}
@@ -348,6 +376,7 @@ static void dax_disassociate_entry(void *entry, struct address_space *mapping,
WARN_ON_ONCE(trunc && page_ref_count(page) > 1);
WARN_ON_ONCE(page->mapping && page->mapping != mapping);
page->mapping = NULL;
+ page->index = 0;
}
}
@@ -364,6 +393,84 @@ static struct page *dax_busy_page(void *entry)
return NULL;
}
+static bool entry_wait_revalidate(void)
+{
+ rcu_read_unlock();
+ schedule();
+ rcu_read_lock();
+
+ /*
+ * Tell __get_unlocked_mapping_entry() to take a break, we need
+ * to revalidate page->mapping after dropping locks
+ */
+ return true;
+}
+
+bool dax_lock_mapping_entry(struct page *page)
+{
+ pgoff_t index;
+ struct inode *inode;
+ bool did_lock = false;
+ void *entry = NULL, **slot;
+ struct address_space *mapping;
+
+ rcu_read_lock();
+ for (;;) {
+ mapping = READ_ONCE(page->mapping);
+
+ if (!dax_mapping(mapping))
+ break;
+
+ /*
+ * In the device-dax case there's no need to lock, a
+ * struct dev_pagemap pin is sufficient to keep the
+ * inode alive, and we assume we have dev_pagemap pin
+ * otherwise we would not have a valid pfn_to_page()
+ * translation.
+ */
+ inode = mapping->host;
+ if (S_ISCHR(inode->i_mode)) {
+ did_lock = true;
+ break;
+ }
+
+ xa_lock_irq(&mapping->i_pages);
+ if (mapping != page->mapping) {
+ xa_unlock_irq(&mapping->i_pages);
+ continue;
+ }
+ index = page->index;
+
+ entry = __get_unlocked_mapping_entry(mapping, index, &slot,
+ entry_wait_revalidate);
+ if (!entry) {
+ xa_unlock_irq(&mapping->i_pages);
+ break;
+ } else if (IS_ERR(entry)) {
+ WARN_ON_ONCE(PTR_ERR(entry) != -EAGAIN);
+ continue;
+ }
+ lock_slot(mapping, slot);
+ did_lock = true;
+ xa_unlock_irq(&mapping->i_pages);
+ break;
+ }
+ rcu_read_unlock();
+
+ return did_lock;
+}
+
+void dax_unlock_mapping_entry(struct page *page)
+{
+ struct address_space *mapping = page->mapping;
+ struct inode *inode = mapping->host;
+
+ if (S_ISCHR(inode->i_mode))
+ return;
+
+ unlock_mapping_entry(mapping, page->index);
+}
+
/*
* Find radix tree entry at given index. If it points to an exceptional entry,
* return it with the radix tree entry locked. If the radix tree doesn't
@@ -708,7 +815,7 @@ static void *dax_insert_mapping_entry(struct address_space *mapping,
new_entry = dax_radix_locked_entry(pfn, flags);
if (dax_entry_size(entry) != dax_entry_size(new_entry)) {
dax_disassociate_entry(entry, mapping, false);
- dax_associate_entry(new_entry, mapping);
+ dax_associate_entry(new_entry, mapping, vmf->vma, vmf->address);
}
if (dax_is_zero_entry(entry) || dax_is_empty_entry(entry)) {