linux/include
Li Chen 40f356e610 nvdimm: virtio_pmem: stop allocating child flush bio
pmem_submit_bio() passes the parent bio to nvdimm_flush() for
REQ_FUA. For virtio-pmem this makes async_pmem_flush() allocate
and submit a child PREFLUSH bio chained to the parent.

That child allocation is in the block submit path. Making it
blocking with GFP_NOIO can consume the same global bio mempool that
submit_bio() uses, while making it GFP_ATOMIC can fail under
pressure. A forced failure of the child allocation produced:

virtio_pmem: forcing child bio allocation failure for test
Buffer I/O error on dev pmem0, logical block 0, lost sync page write
EXT4-fs (pmem0): I/O error while writing superblock
EXT4-fs (pmem0): mount failed

Avoid the child bio without turning REQ_FUA into a synchronous
submit-path wait. Let provider flush callbacks return
NVDIMM_FLUSH_ASYNC after taking ownership of parent bio completion.
pmem_submit_bio() returns in that case, and virtio-pmem queues an
ordered WQ_MEM_RECLAIM work item that runs the existing host flush
path and completes the parent bio.

This keeps the asynchronous completion model of the child-bio path
while removing the child bio allocation from the submit path.

Signed-off-by: Li Chen <me@linux.beauty>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <20260630092338.2094628-5-me@linux.beauty>
2026-08-19 06:38:45 -04:00
..
acpi ACPI: CPPC: Check all controls for fast switching 2026-07-22 15:09:14 +02:00
asm-generic
clocksource
crypto
cxl
drm Revert "drm/sched: Remove FIFO and RR and simplify to a single run queue" 2026-08-11 17:34:10 +01:00
dt-bindings SoC fixes for 7.2 2026-07-17 08:52:09 -07:00
hyperv mshv: fix hv_input_get_system_property struct 2026-07-22 21:58:21 +00:00
keys
kunit
kvm KVM: arm64: vgic: Fix race between LPI release and re-registration 2026-07-23 09:56:57 +01:00
linux nvdimm: virtio_pmem: stop allocating child flush bio 2026-08-19 06:38:45 -04:00
math-emu
media
memory
misc
net netfilter pull request 26-08-10 2026-08-11 18:32:18 -07:00
pcmcia Replace <linux/mod_devicetable.h> by more specific <linux/device-id/*.h> (headers) 2026-07-03 07:38:16 +02:00
ras
rdma
rv
scsi SCSI fixes on 20260812 2026-08-12 08:03:31 -07:00
soc soc/tegra: pmc: Fixes for v7.2 2026-07-10 14:40:52 +02:00
sound ASoC/soundwire: Intel: reset the PCMSyCM registers in hda_sdw_bpt_close 2026-07-31 13:23:10 +01:00
target
trace for-7.2-rc6-fixup-worker-tag 2026-08-06 13:29:15 -07:00
uapi virtio: Add ID for virtio media 2026-08-19 06:38:44 -04:00
ufs
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xen xen: Replace __ASSEMBLY__ with __ASSEMBLER__ in header files 2026-07-01 09:49:52 +02:00
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