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-rw-r--r--mm/memory-failure.c73
1 files changed, 32 insertions, 41 deletions
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 757f6b0accf..2044fe8920c 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -7,21 +7,26 @@
* Free Software Foundation.
*
* High level machine check handler. Handles pages reported by the
- * hardware as being corrupted usually due to a 2bit ECC memory or cache
+ * hardware as being corrupted usually due to a multi-bit ECC memory or cache
* failure.
+ *
+ * In addition there is a "soft offline" entry point that allows stop using
+ * not-yet-corrupted-by-suspicious pages without killing anything.
*
* Handles page cache pages in various states. The tricky part
- * here is that we can access any page asynchronous to other VM
- * users, because memory failures could happen anytime and anywhere,
- * possibly violating some of their assumptions. This is why this code
- * has to be extremely careful. Generally it tries to use normal locking
- * rules, as in get the standard locks, even if that means the
- * error handling takes potentially a long time.
- *
- * The operation to map back from RMAP chains to processes has to walk
- * the complete process list and has non linear complexity with the number
- * mappings. In short it can be quite slow. But since memory corruptions
- * are rare we hope to get away with this.
+ * here is that we can access any page asynchronously in respect to
+ * other VM users, because memory failures could happen anytime and
+ * anywhere. This could violate some of their assumptions. This is why
+ * this code has to be extremely careful. Generally it tries to use
+ * normal locking rules, as in get the standard locks, even if that means
+ * the error handling takes potentially a long time.
+ *
+ * There are several operations here with exponential complexity because
+ * of unsuitable VM data structures. For example the operation to map back
+ * from RMAP chains to processes has to walk the complete process list and
+ * has non linear complexity with the number. But since memory corruptions
+ * are rare we hope to get away with this. This avoids impacting the core
+ * VM.
*/
/*
@@ -30,7 +35,6 @@
* - kcore/oldmem/vmcore/mem/kmem check for hwpoison pages
* - pass bad pages to kdump next kernel
*/
-#define DEBUG 1 /* remove me in 2.6.34 */
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/page-flags.h>
@@ -78,7 +82,7 @@ static int hwpoison_filter_dev(struct page *p)
return 0;
/*
- * page_mapping() does not accept slab page
+ * page_mapping() does not accept slab pages.
*/
if (PageSlab(p))
return -EINVAL;
@@ -268,7 +272,7 @@ struct to_kill {
struct list_head nd;
struct task_struct *tsk;
unsigned long addr;
- unsigned addr_valid:1;
+ char addr_valid;
};
/*
@@ -309,7 +313,7 @@ static void add_to_kill(struct task_struct *tsk, struct page *p,
* a SIGKILL because the error is not contained anymore.
*/
if (tk->addr == -EFAULT) {
- pr_debug("MCE: Unable to find user space address %lx in %s\n",
+ pr_info("MCE: Unable to find user space address %lx in %s\n",
page_to_pfn(p), tsk->comm);
tk->addr_valid = 0;
}
@@ -577,7 +581,7 @@ static int me_pagecache_clean(struct page *p, unsigned long pfn)
pfn, err);
} else if (page_has_private(p) &&
!try_to_release_page(p, GFP_NOIO)) {
- pr_debug("MCE %#lx: failed to release buffers\n", pfn);
+ pr_info("MCE %#lx: failed to release buffers\n", pfn);
} else {
ret = RECOVERED;
}
@@ -836,8 +840,6 @@ static int page_action(struct page_state *ps, struct page *p,
return (result == RECOVERED || result == DELAYED) ? 0 : -EBUSY;
}
-#define N_UNMAP_TRIES 5
-
/*
* Do all that is necessary to remove user space mappings. Unmap
* the pages and send SIGBUS to the processes if the data was dirty.
@@ -849,7 +851,6 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
struct address_space *mapping;
LIST_HEAD(tokill);
int ret;
- int i;
int kill = 1;
struct page *hpage = compound_head(p);
@@ -903,17 +904,7 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
if (kill)
collect_procs(hpage, &tokill);
- /*
- * try_to_unmap can fail temporarily due to races.
- * Try a few times (RED-PEN better strategy?)
- */
- for (i = 0; i < N_UNMAP_TRIES; i++) {
- ret = try_to_unmap(hpage, ttu);
- if (ret == SWAP_SUCCESS)
- break;
- pr_debug("MCE %#lx: try_to_unmap retry needed %d\n", pfn, ret);
- }
-
+ ret = try_to_unmap(hpage, ttu);
if (ret != SWAP_SUCCESS)
printk(KERN_ERR "MCE %#lx: failed to unmap page (mapcount=%d)\n",
pfn, page_mapcount(hpage));
@@ -1147,7 +1138,7 @@ int unpoison_memory(unsigned long pfn)
page = compound_head(p);
if (!PageHWPoison(p)) {
- pr_debug("MCE: Page was already unpoisoned %#lx\n", pfn);
+ pr_info("MCE: Page was already unpoisoned %#lx\n", pfn);
return 0;
}
@@ -1156,7 +1147,7 @@ int unpoison_memory(unsigned long pfn)
if (!get_page_unless_zero(page)) {
if (TestClearPageHWPoison(p))
atomic_long_sub(nr_pages, &mce_bad_pages);
- pr_debug("MCE: Software-unpoisoned free page %#lx\n", pfn);
+ pr_info("MCE: Software-unpoisoned free page %#lx\n", pfn);
return 0;
}
@@ -1168,7 +1159,7 @@ int unpoison_memory(unsigned long pfn)
* the free buddy page pool.
*/
if (TestClearPageHWPoison(page)) {
- pr_debug("MCE: Software-unpoisoned page %#lx\n", pfn);
+ pr_info("MCE: Software-unpoisoned page %#lx\n", pfn);
atomic_long_sub(nr_pages, &mce_bad_pages);
freeit = 1;
}
@@ -1217,12 +1208,12 @@ static int get_any_page(struct page *p, unsigned long pfn, int flags)
set_migratetype_isolate(p);
if (!get_page_unless_zero(compound_head(p))) {
if (is_free_buddy_page(p)) {
- pr_debug("get_any_page: %#lx free buddy page\n", pfn);
+ pr_info("get_any_page: %#lx free buddy page\n", pfn);
/* Set hwpoison bit while page is still isolated */
SetPageHWPoison(p);
ret = 0;
} else {
- pr_debug("get_any_page: %#lx: unknown zero refcount page type %lx\n",
+ pr_info("get_any_page: %#lx: unknown zero refcount page type %lx\n",
pfn, p->flags);
ret = -EIO;
}
@@ -1288,7 +1279,7 @@ int soft_offline_page(struct page *page, int flags)
goto done;
}
if (!PageLRU(page)) {
- pr_debug("soft_offline: %#lx: unknown non LRU page type %lx\n",
+ pr_info("soft_offline: %#lx: unknown non LRU page type %lx\n",
pfn, page->flags);
return -EIO;
}
@@ -1302,7 +1293,7 @@ int soft_offline_page(struct page *page, int flags)
if (PageHWPoison(page)) {
unlock_page(page);
put_page(page);
- pr_debug("soft offline: %#lx page already poisoned\n", pfn);
+ pr_info("soft offline: %#lx page already poisoned\n", pfn);
return -EBUSY;
}
@@ -1323,7 +1314,7 @@ int soft_offline_page(struct page *page, int flags)
put_page(page);
if (ret == 1) {
ret = 0;
- pr_debug("soft_offline: %#lx: invalidated\n", pfn);
+ pr_info("soft_offline: %#lx: invalidated\n", pfn);
goto done;
}
@@ -1339,13 +1330,13 @@ int soft_offline_page(struct page *page, int flags)
list_add(&page->lru, &pagelist);
ret = migrate_pages(&pagelist, new_page, MPOL_MF_MOVE_ALL, 0);
if (ret) {
- pr_debug("soft offline: %#lx: migration failed %d, type %lx\n",
+ pr_info("soft offline: %#lx: migration failed %d, type %lx\n",
pfn, ret, page->flags);
if (ret > 0)
ret = -EIO;
}
} else {
- pr_debug("soft offline: %#lx: isolation failed: %d, page count %d, type %lx\n",
+ pr_info("soft offline: %#lx: isolation failed: %d, page count %d, type %lx\n",
pfn, ret, page_count(page), page->flags);
}
if (ret)
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2024-12-26 10:52:15 +0000