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0ea7eeec24
Add an option for pcpu_alloc() to support __GFP_NOWARN flag. Currently, we always throw a warning when size or alignment is unsupported (and also dump stack on failed allocation requests). The warning itself is harmless since we return NULL anyway for any failed request, which callers are required to handle anyway. However, it becomes harmful when panic_on_warn is set. The rationale for the WARN() in pcpu_alloc() is that it can be tracked when larger than supported allocation requests are made such that allocations limits can be tweaked if warranted. This makes sense for in-kernel users, however, there are users of pcpu allocator where allocation size is derived from user space requests, e.g. when creating BPF maps. In these cases, the requests should fail gracefully without throwing a splat. The current work-around was to check allocation size against the upper limit of PCPU_MIN_UNIT_SIZE from call-sites for bailing out prior to a call to pcpu_alloc() in order to avoid throwing the WARN(). This is bad in multiple ways since PCPU_MIN_UNIT_SIZE is an implementation detail, and having the checks on call-sites only complicates the code for no good reason. Thus, lets fix it generically by supporting the __GFP_NOWARN flag that users can then use with calling the __alloc_percpu_gfp() helper instead. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Tejun Heo <tj@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net> |
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Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.