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ufs: Avoid M_WAITOK allocations when building a dirhash

Description

ufs: Avoid M_WAITOK allocations when building a dirhash

At this point the directory's vnode lock is held, so blocking while
waiting for free pages makes the system more susceptible to deadlock in
low memory conditions. This is particularly problematic on NUMA systems
as UMA currently implements a strict first-touch policy.

ufsdirhash_build() already uses M_NOWAIT for other allocations and
already handled failures for the block array allocation, so just convert
to M_NOWAIT.

PR: 253992
Reviewed by: markj, mckusick, vangyzen

(cherry picked from commit f17a5900850b4d449a91cbe9c61dfb62373c3cd1)

Details

Provenance
dgmorris_earthlink.netAuthored on May 20 2021, 2:54 PM
markjCommitted on May 27 2021, 1:05 PM
Parents
rG7fd88ba72eb3: netgraph/ng_bridge: Avoid cache thrashing
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