mm: warn about illegal __GFP_NOFAIL usage in a more appropriate location and manner

Three points for this change:

1. We should consolidate all warnings in one place. Currently, the
order > 1 war

mm: warn about illegal __GFP_NOFAIL usage in a more appropriate location and manner

Three points for this change:

1. We should consolidate all warnings in one place. Currently, the
order > 1 warning is in the hotpath, while others are in less
likely scenarios. Moving all warnings to the slowpath will reduce
the overhead for order > 1 and increase the visibility of other
warnings.

2. We currently have two warnings for order: one for order > 1 in
the hotpath and another for order > costly_order in the laziest
path. I suggest standardizing on order > 1 since it's been in
use for a long time.

3. We don't need to check for __GFP_NOWARN in this case. __GFP_NOWARN
is meant to suppress allocation failure reports, but here we're
dealing with bug detection, not allocation failures. So replace
WARN_ON_ONCE_GFP by WARN_ON_ONCE.

[[email protected]: also update the doc for __GFP_NOFAIL with order > 1]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Barry Song <[email protected]>
Suggested-by: Vlastimil Babka <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: "Eugenio Pérez" <[email protected]>
Cc: Hailong.Liu <[email protected]>
Cc: Hyeonggon Yoo <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Cc: Maxime Coquelin <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Uladzislau Rezki (Sony) <[email protected]>
Cc: Xie Yongji <[email protected]>
Cc: Xuan Zhuo <[email protected]>
Cc: Yafang Shao <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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mm: document __GFP_NOFAIL must be blockable

Non-blocking allocation with __GFP_NOFAIL is not supported and may still
result in NULL pointers (if we don't return NULL, we result in busy-loop
within n

mm: document __GFP_NOFAIL must be blockable

Non-blocking allocation with __GFP_NOFAIL is not supported and may still
result in NULL pointers (if we don't return NULL, we result in busy-loop
within non-sleepable contexts):

static inline struct page *
__alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
struct alloc_context *ac)
{
...
/*
* Make sure that __GFP_NOFAIL request doesn't leak out and make sure
* we always retry
*/
if (gfp_mask & __GFP_NOFAIL) {
/*
* All existing users of the __GFP_NOFAIL are blockable, so warn
* of any new users that actually require GFP_NOWAIT
*/
if (WARN_ON_ONCE_GFP(!can_direct_reclaim, gfp_mask))
goto fail;
...
}
...
fail:
warn_alloc(gfp_mask, ac->nodemask,
"page allocation failure: order:%u", order);
got_pg:
return page;
}

Highlight this in the documentation of __GFP_NOFAIL so that non-mm
subsystems can reject any illegal usage of __GFP_NOFAIL with GFP_ATOMIC,
GFP_NOWAIT, etc.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Barry Song <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Acked-by: Davidlohr Bueso <[email protected]>
Acked-by: David Hildenbrand <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: "Eugenio Pérez" <[email protected]>
Cc: Hailong.Liu <[email protected]>
Cc: Hyeonggon Yoo <[email protected]>
Cc: Jason Wang <[email protected]>
Cc: Joonsoo Kim <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Cc: Maxime Coquelin <[email protected]>
Cc: "Michael S. Tsirkin" <[email protected]>
Cc: Pekka Enberg <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Uladzislau Rezki (Sony) <[email protected]>
Cc: Xuan Zhuo <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Xie Yongji <[email protected]>
Cc: Yafang Shao <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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mm: introduce __GFP_NO_OBJ_EXT flag to selectively prevent slabobj_ext creation

Introduce __GFP_NO_OBJ_EXT flag in order to prevent recursive allocations
when allocating slabobj_ext on a slab.

Link

mm: introduce __GFP_NO_OBJ_EXT flag to selectively prevent slabobj_ext creation

Introduce __GFP_NO_OBJ_EXT flag in order to prevent recursive allocations
when allocating slabobj_ext on a slab.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Suren Baghdasaryan <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Reviewed-by: Pasha Tatashin <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]>
Tested-by: Kees Cook <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Alex Gaynor <[email protected]>
Cc: Alice Ryhl <[email protected]>
Cc: Andreas Hindborg <[email protected]>
Cc: Benno Lossin <[email protected]>
Cc: "Björn Roy Baron" <[email protected]>
Cc: Boqun Feng <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: Dennis Zhou <[email protected]>
Cc: Gary Guo <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Miguel Ojeda <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Wedson Almeida Filho <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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memblock tests: fix undefined reference to `BIT'

commit 772dd0342727 ("mm: enumerate all gfp flags") define gfp flags
with the help of BIT, while gfp_types.h doesn't include header file for
the defi

memblock tests: fix undefined reference to `BIT'

commit 772dd0342727 ("mm: enumerate all gfp flags") define gfp flags
with the help of BIT, while gfp_types.h doesn't include header file for
the definition. This through an error on building memblock tests.

Let's include linux/bits.h to fix it.

Signed-off-by: Wei Yang <[email protected]>
CC: Suren Baghdasaryan <[email protected]>
CC: Michal Hocko <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mike Rapoport (IBM) <[email protected]>

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mm: enumerate all gfp flags

Introduce GFP bits enumeration to let compiler track the number of used
bits (which depends on the config options) instead of hardcoding them.
That simplifies __GFP_BITS

mm: enumerate all gfp flags

Introduce GFP bits enumeration to let compiler track the number of used
bits (which depends on the config options) instead of hardcoding them.
That simplifies __GFP_BITS_SHIFT calculation.

Link: https://lkml.kernel.org/r/[email protected]
Suggested-by: Petr Tesařík <[email protected]>
Signed-off-by: Suren Baghdasaryan <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Reviewed-by: Pasha Tatashin <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Kent Overstreet <[email protected]>
Cc: Petr Tesarik <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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gfp: gfp_types.h: fix typos & punctuation

Correct typos/spellos and punctutation.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Randy Dunlap <rdunlap@i

gfp: gfp_types.h: fix typos & punctuation

Correct typos/spellos and punctutation.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Randy Dunlap <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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gfp: include __GFP_NOWARN in GFP_NOWAIT

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

gfp: include __GFP_NOWARN in GFP_NOWAIT

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/[email protected]
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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kasan: remove PG_skip_kasan_poison flag

Code inspection reveals that PG_skip_kasan_poison is redundant with
kasantag, because the former is intended to be set iff the latter is the
match-all tag. I

kasan: remove PG_skip_kasan_poison flag

Code inspection reveals that PG_skip_kasan_poison is redundant with
kasantag, because the former is intended to be set iff the latter is the
match-all tag. It can also be observed that it's basically pointless to
poison pages which have kasantag=0, because any pages with this tag would
have been pointed to by pointers with match-all tags, so poisoning the
pages would have little to no effect in terms of bug detection.
Therefore, change the condition in should_skip_kasan_poison() to check
kasantag instead, and remove PG_skip_kasan_poison and associated flags.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://linux-review.googlesource.com/id/I57f825f2eaeaf7e8389d6cf4597c8a5821359838
Signed-off-by: Peter Collingbourne <[email protected]>
Reviewed-by: Andrey Konovalov <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: Evgenii Stepanov <[email protected]>
Cc: Vincenzo Frascino <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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mm: discard __GFP_ATOMIC

__GFP_ATOMIC serves little purpose. Its main effect is to set
ALLOC_HARDER which adds a few little boosts to increase the chance of an
allocation succeeding, one of which i

mm: discard __GFP_ATOMIC

__GFP_ATOMIC serves little purpose. Its main effect is to set
ALLOC_HARDER which adds a few little boosts to increase the chance of an
allocation succeeding, one of which is to lower the water-mark at which it
will succeed.

It is *always* paired with __GFP_HIGH which sets ALLOC_HIGH which also
adjusts this watermark. It is probable that other users of __GFP_HIGH
should benefit from the other little bonuses that __GFP_ATOMIC gets.

__GFP_ATOMIC also gives a warning if used with __GFP_DIRECT_RECLAIM.
There is little point to this. We already get a might_sleep() warning if
__GFP_DIRECT_RECLAIM is set.

__GFP_ATOMIC allows the "watermark_boost" to be side-stepped. It is
probable that testing ALLOC_HARDER is a better fit here.

__GFP_ATOMIC is used by tegra-smmu.c to check if the allocation might
sleep. This should test __GFP_DIRECT_RECLAIM instead.

This patch:
- removes __GFP_ATOMIC
- allows __GFP_HIGH allocations to ignore watermark boosting as well
as GFP_ATOMIC requests.
- makes other adjustments as suggested by the above.

The net result is not change to GFP_ATOMIC allocations. Other
allocations that use __GFP_HIGH will benefit from a few different extra
privileges. This affects:
xen, dm, md, ntfs3
the vermillion frame buffer
hibernation
ksm
swap
all of which likely produce more benefit than cost if these selected
allocation are more likely to succeed quickly.

[mgorman: Minor adjustments to rework on top of a series]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: NeilBrown <[email protected]>
Signed-off-by: Mel Gorman <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Thierry Reding <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

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headers/deps: mm: Split <linux/gfp_types.h> out of <linux/gfp.h>

This is a much smaller header.

Signed-off-by: Ingo Molnar <[email protected]>
Signed-off-by: Yury Norov <[email protected]>