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docs/core-api: memory-allocation: GFP_NOWAIT doesn't need __GFP_NOWARN

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Since v6.8 the definition of GFP_NOWAIT has implied __GFP_NOWARN,
so it is now redundant to add this flag explicitly.

Update the docs to match, and emphasise the need for a fallback
when using GFP_NOWAIT.

Fixes: 16f5dfbc85 ("gfp: include __GFP_NOWARN in GFP_NOWAIT")
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20240729140127.244606-1-Dave.Martin@arm.com
This commit is contained in:
Dave Martin 2024-07-29 15:01:27 +01:00 committed by Jonathan Corbet
parent 8400291e28
commit b745fdeff5
1 changed files with 3 additions and 2 deletions
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5
Documentation/core-api/memory-allocation.rst
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@ -45,8 +45,9 @@ here we briefly outline their recommended usage:
* If the allocation is performed from an atomic context, e.g interrupt * If the allocation is performed from an atomic context, e.g interrupt
handler, use ``GFP_NOWAIT``. This flag prevents direct reclaim and handler, use ``GFP_NOWAIT``. This flag prevents direct reclaim and
IO or filesystem operations. Consequently, under memory pressure IO or filesystem operations. Consequently, under memory pressure
``GFP_NOWAIT`` allocation is likely to fail. Allocations which ``GFP_NOWAIT`` allocation is likely to fail. Users of this flag need
have a reasonable fallback should be using ``GFP_NOWARN``. to provide a suitable fallback to cope with such failures where
appropriate.
* If you think that accessing memory reserves is justified and the kernel * If you think that accessing memory reserves is justified and the kernel
will be stressed unless allocation succeeds, you may use ``GFP_ATOMIC``. will be stressed unless allocation succeeds, you may use ``GFP_ATOMIC``.
* Untrusted allocations triggered from userspace should be a subject * Untrusted allocations triggered from userspace should be a subject