linux-stable.git/mm/memory-failure.c, branch linux-6.3.y

mm/hwpoison: convert TTU_IGNORE_HWPOISON to TTU_HWPOISON

2023-02-28T01:00:14+00:00

After a memory error happens on a clean folio, a process unexpectedly
receives SIGBUS when it accesses the error page.  This SIGBUS killing is
pointless and simply degrades the level of RAS of the system, because the
clean folio can be dropped without any data lost on memory error handling
as we do for a clean pagecache.

When memory_failure() is called on a clean folio, try_to_unmap() is called
twice (one from split_huge_page() and one from hwpoison_user_mappings()). 
The root cause of the issue is that pte conversion to hwpoisoned entry is
now done in the first call of try_to_unmap() because PageHWPoison is
already set at this point, while it's actually expected to be done in the
second call.  This behavior disturbs the error handling operation like
removing pagecache, which results in the malfunction described above.

So convert TTU_IGNORE_HWPOISON into TTU_HWPOISON and set TTU_HWPOISON only
when we really intend to convert pte to hwpoison entry.  This can prevent
other callers of try_to_unmap() from accidentally converting to hwpoison
entries.

Link: https://lkml.kernel.org/r/20230221085905.1465385-1-naoya.horiguchi@linux.dev
Fixes: a42634a6c07d ("readahead: Use a folio in read_pages()")
Signed-off-by: Naoya Horiguchi 
Cc: David Hildenbrand 
Cc: Hugh Dickins 
Cc: Matthew Wilcox 
Cc: Miaohe Lin 
Cc: Minchan Kim 
Cc: Vlastimil Babka 
Cc: 
Signed-off-by: Andrew Morton

mm: change to return bool for isolate_movable_page()

2023-02-20T20:46:17+00:00

Now the isolate_movable_page() can only return 0 or -EBUSY, and no users
will care about the negative return value, thus we can convert the
isolate_movable_page() to return a boolean value to make the code more
clear when checking the movable page isolation state.

No functional changes intended.

[akpm@linux-foundation.org: remove unneeded comment, per Matthew]
Link: https://lkml.kernel.org/r/cb877f73f4fff8d309611082ec740a7065b1ade0.1676424378.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang 
Acked-by: David Hildenbrand 
Reviewed-by: Matthew Wilcox (Oracle) 
Acked-by: Linus Torvalds 
Reviewed-by: SeongJae Park 
Signed-off-by: Andrew Morton

mm: hugetlb: change to return bool for isolate_hugetlb()

2023-02-20T20:46:17+00:00

Now the isolate_hugetlb() only returns 0 or -EBUSY, and most users did not
care about the negative value, thus we can convert the isolate_hugetlb()
to return a boolean value to make code more clear when checking the
hugetlb isolation state.  Moreover converts 2 users which will consider
the negative value returned by isolate_hugetlb().

No functional changes intended.

[akpm@linux-foundation.org: shorten locked section, per SeongJae Park]
Link: https://lkml.kernel.org/r/12a287c5bebc13df304387087bbecc6421510849.1676424378.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang 
Acked-by: David Hildenbrand 
Reviewed-by: Matthew Wilcox (Oracle) 
Reviewed-by: Mike Kravetz 
Acked-by: Linus Torvalds 
Reviewed-by: SeongJae Park 
Signed-off-by: Andrew Morton

mm: change to return bool for isolate_lru_page()

2023-02-20T20:46:17+00:00

The isolate_lru_page() can only return 0 or -EBUSY, and most users did not
care about the negative error of isolate_lru_page(), except one user in
add_page_for_migration().  So we can convert the isolate_lru_page() to
return a boolean value, which can help to make the code more clear when
checking the return value of isolate_lru_page().

Also convert all users' logic of checking the isolation state.

No functional changes intended.

Link: https://lkml.kernel.org/r/3074c1ab628d9dbf139b33f248a8bc253a3f95f0.1676424378.git.baolin.wang@linux.alibaba.com
Signed-off-by: Baolin Wang 
Acked-by: David Hildenbrand 
Reviewed-by: Matthew Wilcox (Oracle) 
Acked-by: Linus Torvalds 
Reviewed-by: SeongJae Park 
Signed-off-by: Andrew Morton

mm/hugetlb: convert isolate_hugetlb to folios

2023-02-13T23:54:26+00:00

Patch series "continue hugetlb folio conversion", v3.

This series continues the conversion of core hugetlb functions to use
folios. This series converts many helper funtions in the hugetlb fault
path. This is in preparation for another series to convert the hugetlb
fault code paths to operate on folios.


This patch (of 8):

Convert isolate_hugetlb() to take in a folio and convert its callers to
pass a folio.  Use page_folio() to convert the callers to use a folio is
safe as isolate_hugetlb() operates on a head page.

Link: https://lkml.kernel.org/r/20230113223057.173292-1-sidhartha.kumar@oracle.com
Link: https://lkml.kernel.org/r/20230113223057.173292-2-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar 
Reviewed-by: Mike Kravetz 
Cc: John Hubbard 
Cc: Matthew Wilcox 
Cc: Mike Kravetz 
Cc: Muchun Song 
Signed-off-by: Andrew Morton

mm: memory-failure: bump memory failure stats to pglist_data

2023-02-03T06:33:28+00:00

Right before memory_failure finishes its handling, accumulate poisoned
page's resolution counters to pglist_data's memory_failure_stats, so as to
update the corresponding sysfs entries.

Tested:
1) Start an application to allocate memory buffer chunks
2) Convert random memory buffer addresses to physical addresses
3) Inject memory errors using EINJ at chosen physical addresses
4) Access poisoned memory buffer and recover from SIGBUS
5) Check counter values under
   /sys/devices/system/node/node*/memory_failure/*

Link: https://lkml.kernel.org/r/20230120034622.2698268-3-jiaqiyan@google.com
Signed-off-by: Jiaqi Yan 
Acked-by: David Rientjes 
Acked-by: Naoya Horiguchi 
Cc: Kefeng Wang 
Cc: Tony Luck 
Cc: Yang Shi 
Signed-off-by: Andrew Morton

mm: memory-failure: add memory failure stats to sysfs

2023-02-03T06:33:28+00:00

Patch series "Introduce per NUMA node memory error statistics", v2.

Background
==========

In the RFC for Kernel Support of Memory Error Detection [1], one advantage
of software-based scanning over hardware patrol scrubber is the ability to
make statistics visible to system administrators.  The statistics include
2 categories:

* Memory error statistics, for example, how many memory error are
  encountered, how many of them are recovered by the kernel.  Note these
  memory errors are non-fatal to kernel: during the machine check
  exception (MCE) handling kernel already classified MCE's severity to be
  unnecessary to panic (but either action required or optional).

* Scanner statistics, for example how many times the scanner have fully
  scanned a NUMA node, how many errors are first detected by the scanner.

The memory error statistics are useful to userspace and actually not
specific to scanner detected memory errors, and are the focus of this
patchset.

Motivation
==========

Memory error stats are important to userspace but insufficient in kernel
today.  Datacenter administrators can better monitor a machine's memory
health with the visible stats.  For example, while memory errors are
inevitable on servers with 10+ TB memory, starting server maintenance when
there are only 1~2 recovered memory errors could be overreacting; in cloud
production environment maintenance usually means live migrate all the
workload running on the server and this usually causes nontrivial
disruption to the customer.  Providing insight into the scope of memory
errors on a system helps to determine the appropriate follow-up action. 
In addition, the kernel's existing memory error stats need to be
standardized so that userspace can reliably count on their usefulness.

Today kernel provides following memory error info to userspace, but they
are not sufficient or have disadvantages:
* HardwareCorrupted in /proc/meminfo: number of bytes poisoned in total,
  not per NUMA node stats though
* ras:memory_failure_event: only available after explicitly enabled
* /dev/mcelog provides many useful info about the MCEs, but doesn't
  capture how memory_failure recovered memory MCEs
* kernel logs: userspace needs to process log text

Exposing memory error stats is also a good start for the in-kernel memory
error detector.  Today the data source of memory error stats are either
direct memory error consumption, or hardware patrol scrubber detection
(either signaled as UCNA or SRAO).  Once in-kernel memory scanner is
implemented, it will be the main source as it is usually configured to
scan memory DIMMs constantly and faster than hardware patrol scrubber.

How Implemented
===============

As Naoya pointed out [2], exposing memory error statistics to userspace is
useful independent of software or hardware scanner.  Therefore we
implement the memory error statistics independent of the in-kernel memory
error detector.  It exposes the following per NUMA node memory error
counters:

  /sys/devices/system/node/node${X}/memory_failure/total
  /sys/devices/system/node/node${X}/memory_failure/recovered
  /sys/devices/system/node/node${X}/memory_failure/ignored
  /sys/devices/system/node/node${X}/memory_failure/failed
  /sys/devices/system/node/node${X}/memory_failure/delayed

These counters describe how many raw pages are poisoned and after the
attempted recoveries by the kernel, their resolutions: how many are
recovered, ignored, failed, or delayed respectively.  This approach can be
easier to extend for future use cases than /proc/meminfo, trace event, and
log.  The following math holds for the statistics:

* total = recovered + ignored + failed + delayed

These memory error stats are reset during machine boot.

The 1st commit introduces these sysfs entries.  The 2nd commit populates
memory error stats every time memory_failure attempts memory error
recovery.  The 3rd commit adds documentations for introduced stats.

[1] https://lore.kernel.org/linux-mm/7E670362-C29E-4626-B546-26530D54F937@gmail.com/T/#mc22959244f5388891c523882e61163c6e4d703af
[2] https://lore.kernel.org/linux-mm/7E670362-C29E-4626-B546-26530D54F937@gmail.com/T/#m52d8d7a333d8536bd7ce74253298858b1c0c0ac6


This patch (of 3):

Today kernel provides following memory error info to userspace, but each
has its own disadvantage

* HardwareCorrupted in /proc/meminfo: number of bytes poisoned in total,
  not per NUMA node stats though

* ras:memory_failure_event: only available after explicitly enabled

* /dev/mcelog provides many useful info about the MCEs, but
  doesn't capture how memory_failure recovered memory MCEs

* kernel logs: userspace needs to process log text

Exposes per NUMA node memory error stats as sysfs entries:

  /sys/devices/system/node/node${X}/memory_failure/total
  /sys/devices/system/node/node${X}/memory_failure/recovered
  /sys/devices/system/node/node${X}/memory_failure/ignored
  /sys/devices/system/node/node${X}/memory_failure/failed
  /sys/devices/system/node/node${X}/memory_failure/delayed

These counters describe how many raw pages are poisoned and after the
attempted recoveries by the kernel, their resolutions: how many are
recovered, ignored, failed, or delayed respectively.  The following math
holds for the statistics:

* total = recovered + ignored + failed + delayed

Link: https://lkml.kernel.org/r/20230120034622.2698268-1-jiaqiyan@google.com
Link: https://lkml.kernel.org/r/20230120034622.2698268-2-jiaqiyan@google.com
Signed-off-by: Jiaqi Yan 
Acked-by: David Rientjes 
Acked-by: Naoya Horiguchi 
Cc: Kefeng Wang 
Cc: Tony Luck 
Cc: Yang Shi 
Signed-off-by: Andrew Morton

mm/hugetlb: convert get_hwpoison_huge_page() to folios

2023-02-03T06:33:23+00:00

Straightforward conversion of get_hwpoison_huge_page() to
get_hwpoison_hugetlb_folio().  Reduces two references to a head page in
memory-failure.c

[arnd@arndb.de: fix get_hwpoison_hugetlb_folio() stub]
  Link: https://lkml.kernel.org/r/20230119111920.635260-1-arnd@kernel.org
Link: https://lkml.kernel.org/r/20230118174039.14247-1-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar 
Signed-off-by: Arnd Bergmann 
Acked-by: Naoya Horiguchi 
Reviewed-by: Matthew Wilcox (Oracle) 
Cc: Mike Kravetz 
Cc: Muchun Song 
Signed-off-by: Andrew Morton

mm: clean up mlock_page / munlock_page references in comments

2023-02-03T06:33:20+00:00

Change documentation and comments that refer to now-renamed functions.

Link: https://lkml.kernel.org/r/20230116192827.2146732-5-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) 
Signed-off-by: Andrew Morton

mm/memory-failure: convert unpoison_memory() to folios

2023-02-03T06:33:03+00:00

Use a folio inside unpoison_memory which replaces a compound_head() call
with a call to page_folio().

Link: https://lkml.kernel.org/r/20230112204608.80136-9-sidhartha.kumar@oracle.com
Signed-off-by: Sidhartha Kumar 
Acked-by: Naoya Horiguchi 
Cc: Matthew Wilcox 
Cc: Miaohe Lin 
Signed-off-by: Andrew Morton