Add stack_depot_put, a function that decrements the reference counter on a
stack record and removes it from the stack depot once the counter reaches
0.

Internally, when removing a stack record, the function unlinks it from the
hash table bucket and returns to the freelist.

With this change, the users of stack depot can call stack_depot_put when
keeping a stack trace in the stack depot is not needed anymore.  This
allows avoiding polluting the stack depot with irrelevant stack traces and
thus have more space to store the relevant ones before the stack depot
reaches its capacity.

Link: https://lkml.kernel.org/r/1d1ad5692ee43d4fc2b3fd9d221331d30b36123f.1700502145.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Add a reference counter for how many times a stack records has been
  added to stack depot.

Add a new STACK_DEPOT_FLAG_GET flag to stack_depot_save_flags that
  instructs the stack depot to increment the refcount.

Do not yet decrement the refcount; this is implemented in one of the
  following patches.

Do not yet enable any users to use the flag to avoid overflowing the
  refcount.

This is preparatory patch for implementing the eviction of stack records
  from the stack depot.

Link: https://lkml.kernel.org/r/a3fc14a2359d019d2a008d4ff8b46a665371ffee.1700502145.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Change the bool can_alloc argument of __stack_depot_save to a u32
  argument that accepts a set of flags.

The following patch will add another flag to stack_depot_save_flags
  besides the existing STACK_DEPOT_FLAG_CAN_ALLOC.

Also rename the function to stack_depot_save_flags, as
  __stack_depot_save is a cryptic name,

Link: https://lkml.kernel.org/r/645fa15239621eebbd3a10331e5864b718839512.1700502145.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Make KMSAN use stack_depot_save instead of __stack_depot_save, as it
  always passes true to __stack_depot_save as the last argument.

Link: https://lkml.kernel.org/r/18092240699efdc6acd78b51e41ea782953e6c8d.1700502145.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Switch stack_record to use list_head for links in the hash table and in
  the freelist.

This will allow removing entries from the hash table buckets.

This is preparatory patch for implementing the eviction of stack records
  from the stack depot.

Link: https://lkml.kernel.org/r/4787d9a584cd33433d9ee1846b17fa3d3e1987ad.1700502145.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Currently, stack depot uses the following locking scheme:

1. Lock-free accesses when looking up a stack record, which allows to
   have multiple users to look up records in parallel;
2. Spinlock for protecting the stack depot pools and the hash table
   when adding a new record.

For implementing the eviction of stack traces from stack depot, the
  lock-free approach is not going to work anymore, as we will need to be
  able to also remove records from the hash table.

Convert the spinlock into a read/write lock, and drop the atomic
  accesses, as they are no longer required.

Looking up stack traces is now protected by the read lock and adding new
  records - by the write lock.  One of the following patches will add a
  new function for evicting stack records, which will be protected by the
  write lock as well.

With this change, multiple users can still look up records in parallel.

This is preparatory patch for implementing the eviction of stack records
  from the stack depot.

Link: https://lkml.kernel.org/r/9f81ffcc4bb422ebb6326a65a770bf1918634cbb.1700502145.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Instead of using the global pool_offset variable to find a free slot when
storing a new stack record, mainlain a freelist of free slots within the
allocated stack pools.

A global next_stack variable is used as the head of the freelist, and the
next field in the stack_record struct is reused as freelist link (when the
record is not in the freelist, this field is used as a link in the hash
table).

This is preparatory patch for implementing the eviction of stack records
from the stack depot.

Link: https://lkml.kernel.org/r/b9e4c79955c2121b69301778643b203d3fb09ccc.1700502145.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Instead of using the last pointer in stack_pools for storing the pointer
to a new pool (which does not yet store any stack records), use a new
new_pool variable.

This a purely code readability change: it seems more logical to store the
pointer to a pool with a special meaning in a dedicated variable.

Link: https://lkml.kernel.org/r/448bc18296c16bef95cb3167697be6583dcc8ce3.1700502145.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Rename next_pool_required to new_pool_required.

This a purely code readability change: the following patch will change
stack depot to store the pointer to the new pool in a separate variable,
and "new" seems like a more logical name.

Link: https://lkml.kernel.org/r/fd7cd6c6eb250c13ec5d2009d75bb4ddd1470db9.1700502145.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Split code in depot_alloc_stack and depot_init_pool into 3 functions:

1. depot_keep_next_pool that keeps preallocated memory for the next pool
   if required.

2. depot_update_pools that moves on to the next pool if there's no space
   left in the current pool, uses preallocated memory for the new current
   pool if required, and calls depot_keep_next_pool otherwise.

3. depot_alloc_stack that calls depot_update_pools and then allocates
   a stack record as before.

This makes it somewhat easier to follow the logic of depot_alloc_stack and
also serves as a preparation for implementing the eviction of stack
records from the stack depot.

Link: https://lkml.kernel.org/r/71fb144d42b701fcb46708d7f4be6801a4a8270e.1700502145.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Drop smp_load_acquire from next_pool_required in depot_init_pool, as both
depot_init_pool and the all smp_store_release's to this variable are
executed under the stack depot lock.

Also simplify and clean up comments accompanying the use of atomic
accesses in the stack depot code.

Link: https://lkml.kernel.org/r/c118ef044d8db80248d9e1f14592c72e8429e9d9.1700502145.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Instead of storing stack records in stack depot pools one right after
another, use fixed-sized slots.

Add a new Kconfig option STACKDEPOT_MAX_FRAMES that allows to select the
size of the slot in frames.  Use 64 as the default value, which is the
maximum stack trace size both KASAN and KMSAN use right now.

Also add descriptions for other stack depot Kconfig options.

This is preparatory patch for implementing the eviction of stack records
from the stack depot.

Link: https://lkml.kernel.org/r/dce7d030a99ff61022509665187fac45b0827298.1700502145.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Add a helper depot_fetch_stack function that fetches the pointer to a
stack record.

With this change, all static depot_* functions now operate on stack pools
and the exported stack_depot_* functions operate on the hash table.

Link: https://lkml.kernel.org/r/170d8c202f29dc8e3d5491ee074d1e9e029a46db.1700502145.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Stack depot doesn't use the valid bit in handles in any way, so drop it.

Link: https://lkml.kernel.org/r/34969bba2ca6e012c6ad071767197dee64dc5723.1700502145.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

The retval local variable in __stack_depot_save has the union type
handle_parts, but the function never uses anything but the union's handle
field.

Define retval simply as depot_stack_handle_t to simplify the code.

Link: https://lkml.kernel.org/r/3b0763c8057a1cf2f200ff250a5f9580ee36a28c.1700502145.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Do not try fetching a stack trace from the stack depot if the
stack_depot_disabled flag is enabled.

Link: https://lkml.kernel.org/r/c3bfa3b7ab00b2e48ab75a3fbb9c67555777cb08.1700502145.git.andreyknvl@google.comSigned-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Marco Elver <elver@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "stackdepot: allow evicting stack traces", v4.

Currently, the stack depot grows indefinitely until it reaches its
capacity.  Once that happens, the stack depot stops saving new stack
traces.

This creates a problem for using the stack depot for in-field testing and
in production.

For such uses, an ideal stack trace storage should:

1. Allow saving fresh stack traces on systems with a large uptime while
   limiting the amount of memory used to store the traces;
2. Have a low performance impact.

Implementing #1 in the stack depot is impossible with the current
keep-forever approach.  This series targets to address that.  Issue #2 is
left to be addressed in a future series.

This series changes the stack depot implementation to allow evicting
unneeded stack traces from the stack depot.  The users of the stack depot
can do that via new stack_depot_save_flags(STACK_DEPOT_FLAG_GET) and
stack_depot_put APIs.

Internal changes to the stack depot code include:

1. Storing stack traces in fixed-frame-sized slots (vs precisely-sized
   slots in the current implementation); the slot size is controlled via
   CONFIG_STACKDEPOT_MAX_FRAMES (default: 64 frames);
2. Keeping available slots in a freelist (vs keeping an offset to the next
   free slot);
3. Using a read/write lock for synchronization (vs a lock-free approach
   combined with a spinlock).

This series also integrates the eviction functionality into KASAN: the
tag-based modes evict stack traces when the corresponding entry leaves the
stack ring, and Generic KASAN evicts stack traces for objects once those
leave the quarantine.

With KASAN, despite wasting some space on rounding up the size of each
stack record, the total memory consumed by stack depot gets saturated due
to the eviction of irrelevant stack traces from the stack depot.

With the tag-based KASAN modes, the average total amount of memory used
for stack traces becomes ~0.5 MB (with the current default stack ring size
of 32k entries and the default CONFIG_STACKDEPOT_MAX_FRAMES of 64).  With
Generic KASAN, the stack traces take up ~1 MB per 1 GB of RAM (as the
quarantine's size depends on the amount of RAM).

However, with KMSAN, the stack depot ends up using ~4x more memory per a
stack trace than before.  Thus, for KMSAN, the stack depot capacity is
increased accordingly.  KMSAN uses a lot of RAM for shadow memory anyway,
so the increased stack depot memory usage will not make a significant
difference.

Other users of the stack depot do not save stack traces as often as KASAN
and KMSAN.  Thus, the increased memory usage is taken as an acceptable
trade-off.  In the future, these other users can take advantage of the
eviction API to limit the memory waste.

There is no measurable boot time performance impact of these changes for
KASAN on x86-64.  I haven't done any tests for arm64 modes (the stack
depot without performance optimizations is not suitable for intended use
of those anyway), but I expect a similar result.  Obtaining and copying
stack trace frames when saving them into stack depot is what takes the
most time.

This series does not yet provide a way to configure the maximum size of
the stack depot externally (e.g.  via a command-line parameter).  This
will be added in a separate series, possibly together with the performance
improvement changes.


This patch (of 22):

Currently, if stack_depot_disable=off is passed to the kernel command-line
after stack_depot_disable=on, stack depot prints a message that it is
disabled, while it is actually enabled.

Fix this by moving printing the disabled message to
stack_depot_early_init.  Place it before the
__stack_depot_early_init_requested check, so that the message is printed
even if early stack depot init has not been requested.

Also drop the stack_table = NULL assignment from disable_stack_depot, as
stack_table is NULL by default.

Link: https://lkml.kernel.org/r/cover.1700502145.git.andreyknvl@google.com
Link: https://lkml.kernel.org/r/73a25c5fff29f3357cd7a9330e85e09bc8da2cbe.1700502145.git.andreyknvl@google.com
Fixes: e1fdc403 ("lib: stackdepot: add support to disable stack depot")
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Change /sys/kernel/debug/kmemleak report format slightly, adding
"(extra info)" to the backtrace header:

from: "  backtrace:"
to:   "  backtrace (crc <cksum>):"

The <cksum> allows a user to see recurring backtraces without
detailed/careful reading of multiline stacks.  So after cycling
kmemleak-test a few times, I know some leaks are repeating.

  bash-5.2# grep backtrace /sys/kernel/debug/kmemleak | wc
     62     186    1792
  bash-5.2# grep backtrace /sys/kernel/debug/kmemleak | sort -u | wc
     37     111    1067

syzkaller parses kmemleak for "unreferenced object" only, so is
unaffected by this change.  Other github repos are moribund.

Link: https://lkml.kernel.org/r/20231116224318.124209-3-jim.cromie@gmail.comSigned-off-by: Jim Cromie <jim.cromie@gmail.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "tweak kmemleak report format".

These 2 patches make minor changes to the report:

1st strips "age <increasing>" from output.  This makes the output
idempotent; unchanging until a new leak is reported.

2nd adds the backtrace.checksum to the "backtrace:" line.  This lets a
user see repeats without actually reading the whole backtrace.  So now
the backtrace line looks like this:

  backtrace (crc 603070071):

I surveyed for un-wanted effects upon users:

Syzkaller parses kmemleak in executor/common_linux.h:
static void check_leaks(char** frames, int nframes)

It just counts occurrences of "unreferenced object", specifically it
does not look for "age", nor would it choke on "crc" being added.

github has 3 repos with "kmemleak" mentioned, all are moribund.
gitlab has 0 hits on "kmemleak".


This patch (of 2):

Displaying age is pretty, but counter-productive; it changes with
current-time, so it surrenders idempotency of the output, which breaks
simple hash-based cataloging of the records by the user.

The trouble: sequential reads, wo new leaks, get new results:

  :#> sum /sys/kernel/debug/kmemleak
  53439    74 /sys/kernel/debug/kmemleak
  :#> sum /sys/kernel/debug/kmemleak
  59066    74 /sys/kernel/debug/kmemleak

and age is why (nothing else changes):

  :#> grep -v age /sys/kernel/debug/kmemleak | sum
  58894    67
  :#> grep -v age /sys/kernel/debug/kmemleak | sum
  58894    67

Since jiffies is already printed in the "comm" line, age adds nothing.

Notably, syzkaller reads kmemleak only for "unreferenced object", and
won't care about this reform of age-ism.  A few moribund github repos
mention it, but don't compile.

Link: https://lkml.kernel.org/r/20231116224318.124209-1-jim.cromie@gmail.com
Link: https://lkml.kernel.org/r/20231116224318.124209-2-jim.cromie@gmail.comSigned-off-by: Jim Cromie <jim.cromie@gmail.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

There were already assertions that we were not passing a tail page to
error_remove_page(), so make the compiler enforce that by converting
everything to pass and use a folio.

Link: https://lkml.kernel.org/r/20231117161447.2461643-7-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Both callers now have a folio, so pass it in.  Nothing downstream was
expecting a tail page; that's asserted in generic_error_remove_page(), for
example.

Link: https://lkml.kernel.org/r/20231117161447.2461643-6-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

This function was already explicitly calling compound_head();
unfortunately the compiler can't know that and elide the redundant calls
to compound_head() buried in page_mapping(), unlock_page(), etc.  Switch
to using a folio, which does let us elide these calls.

Link: https://lkml.kernel.org/r/20231117161447.2461643-5-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

All three callers now have a folio; pass it in instead of the page.
Saves five calls to compound_head().

Link: https://lkml.kernel.org/r/20231117161447.2461643-4-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Replaces three hidden calls to compound_head() with one visible one.

Link: https://lkml.kernel.org/r/20231117161447.2461643-3-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "Convert aops->error_remove_page to ->error_remove_folio".

This is a memory-failure patch series which converts a lot of uses of page
APIs into folio APIs with the usual benefits.  


This patch (of 6):

Replaces three hidden calls to compound_head() with one visible one.
Fix up a few comments while I'm modifying this function.

Link: https://lkml.kernel.org/r/20231117161447.2461643-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20231117161447.2461643-2-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Writeback is for incompressible and idle zram pages.

Link: https://lkml.kernel.org/r/20231115024223.4133148-2-senozhatsky@chromium.orgSigned-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Dmytro Maluka <dmaluka@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

ZRAM_MEMORY_TRACKING enables two features:
- per-entry ac-time tracking
- debugfs interface

The latter one is the reason why memory-tracking depends on DEBUG_FS,
while the former one is used far beyond debugging these days.  Namely
ac-time is used for fine grained writeback of idle entries (pages).

Move ac-time tracking under its own config option so that it can be
enabled (along with writeback) on systems without DEBUG_FS.

[senozhatsky@chromium.org: ifdef fixup, per Dmytro]
  Link: https://lkml.kernel.org/r/20231117013543.540280-1-senozhatsky@chromium.org
Link: https://lkml.kernel.org/r/20231115024223.4133148-1-senozhatsky@chromium.orgSigned-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Dmytro Maluka <dmaluka@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

While investigating some complex memory allocation and free bugs
especially in multi-processes and multi-threads cases, from time to time,
I feel the free stack isn't sufficient as a page can be freed by processes
or threads other than the one allocating it.  And other processes and
threads which free the page often have the exactly same free stack with
the one allocating the page.  We can't know who free the page only through
the free stack though the current page_owner does tell us the pid and tgid
of the one allocating the page.  This makes the bug investigation often
hard.

So this patch adds free pid and tgid in page_owner, so that we can easily
figure out if the freeing is crossing processes or threads.

Link: https://lkml.kernel.org/r/20231114034202.73098-1-v-songbaohua@oppo.comSigned-off-by: Barry Song <v-songbaohua@oppo.com>
Cc: Audra Mitchell <audra@redhat.com>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kassey Li <quic_yingangl@quicinc.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

pte_bad() never existed unlike similar helpers at PMU, PUD, and PGD level.
This was added erroneously and hence should be dropped instead.

Link: https://lkml.kernel.org/r/20231114063456.339652-1-anshuman.khandual@arm.comSigned-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

KASan inline instrumentation can yield up to a 2x performance gain at the
cost of a larger binary.

Make inline instrumentation the default, as suggested in the bug report
below.

When an architecture does not support inline instrumentation, it should
set ARCH_DISABLE_KASAN_INLINE, as done by PowerPC, for instance.

Link: https://lkml.kernel.org/r/20231109155101.186028-1-paul.heidekrueger@tum.deSigned-off-by: Paul Heidekrüger <paul.heidekrueger@tum.de>
Reported-by: Andrey Konovalov <andreyknvl@gmail.com>
Reviewed-by: Marco Elver <elver@google.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=203495Acked-by: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1. There is a "-1" missing in the page number calculation in
   process_vm_rw_core.  While this can't break anything, it can cause
   unnecessary allocations in certain cases:

   Consider handling an iovec ranging over PVM_MAX_PP_ARRAY_COUNT pages
   that is also aligned to a page boundary.  While pp_stack could hold
   references to such an amount of pinned pages, nr_pages yields
   (PVM_MAX_PP_ARRAY + 1) in process_vm_rw_core.  Consequently, a larger
   buffer is allocated with kmalloc for no reason.

   For any page boundary aligned iovec that is a multiple of PAGE_SIZE
   and larger than PVM_MAX_PP_ARRAY_COUNT pages, nr_pages will be too big
   by 1 and thus kmalloc allocates excess space for one more pointer.

2. max_pages_per_loop is constant and there is no reason to have it as
   a variable.  A macro does the job just fine and saves memory.

3. Replaced "sizeof(struct pages *)" with "sizeof(struct page *)" to
   have matching types for allocation and prevent confusion.

Link: https://lkml.kernel.org/r/20231111184859.44264-1-yjnworkstation@gmail.comSigned-off-by: York Jasper Niebuhr <yjnworkstation@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

With commit cf8e8658 ("arch: Remove Itanium (IA-64) architecture"),
there is no need to keep the IA64-specific vma expansion.

Clean up the IA64-specific vma expansion implementation.

Link: https://lkml.kernel.org/r/20231113124728.3974-1-lukas.bulwahn@gmail.comSigned-off-by: Lukas Bulwahn <lukas.bulwahn@gmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

GFP_NOWAIT callers are always prepared for their allocations to fail
because they fail so frequently.  Forcing the callers to remember to add
__GFP_NOWARN is just annoying and leads to an endless stream of patches
for the places where we forgot to add it.

We can now remove __GFP_NOWARN from all the callers which specify
GFP_NOWAIT, but I'd rather wait a cycle and send patches to each
maintainer instead of creating a big pile of merge conflicts.

Link: https://lkml.kernel.org/r/20231109211507.2262419-1-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

The duplication makes it seem like some work is required before uncharging
in the !PageHWPoison case.  But it isn't, so we can simplify the code a
little.

Note the PageMemcgKmem check is redundant, but I've left it in as it
avoids an unnecessary function call.

Link: https://lkml.kernel.org/r/20231108164920.3401565-1-jackmanb@google.comSigned-off-by: Brendan Jackman <jackmanb@google.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

All callers are now converted to call mapping_evict_folio().

Link: https://lkml.kernel.org/r/20231108182809.602073-7-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

The only caller now has a folio, so pass it in and operate on it.  Saves
many page->folio conversions and introduces only one folio->page
conversion when calling isolate_movable_page().

Link: https://lkml.kernel.org/r/20231108182809.602073-6-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Replace the existing head-page logic with folio logic.

Link: https://lkml.kernel.org/r/20231108182809.602073-5-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

We already have the folio and the mapping, so replace the call to
invalidate_inode_page() with mapping_evict_folio().

Link: https://lkml.kernel.org/r/20231108182809.602073-4-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Convert vmf->page to a folio as soon as we're going to use it.  This fixes
a bug if the fault handler returns a tail page with hardware poison; tail
pages have an invalid page->index, so we would fail to unmap the page from
the page tables.  We actually have to unmap the entire folio (or
mapping_evict_folio() will fail), so use unmap_mapping_folio() instead.

This also saves various calls to compound_head() hidden in lock_page(),
put_page(), etc.

Link: https://lkml.kernel.org/r/20231108182809.602073-3-willy@infradead.org
Fixes: 793917d9 ("mm/readahead: Add large folio readahead")
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Patch series "Fix fault handler's handling of poisoned tail pages".

Since introducing the ability to have large folios in the page cache, it's
been possible to have a hwpoisoned tail page returned from the fault
handler.  We handle this situation poorly; failing to remove the affected
page from use.

This isn't a minimal patch to fix it, it's a full conversion of all the
code surrounding it.


This patch (of 6):

invalidate_inode_page() does very little beyond calling
mapping_evict_folio().  Move the check for mapping being NULL into
mapping_evict_folio() and make it available to the rest of the MM for use
in the next few patches.

Link: https://lkml.kernel.org/r/20231108182809.602073-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20231108182809.602073-2-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>