From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
To: "Martin K. Petersen" <martin.petersen@oracle.com>
Cc: Brian King <brking@us.ibm.com>, Hannes Reinecke <hare@suse.com>,
"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
Matthew Wilcox <willy@infradead.org>,
Mike Rapoport <rppt@kernel.org>,
Wen Xiong <wenxiong@linux.ibm.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linux-scsi@vger.kernel.org, target-devel@vger.kernel.org,
Hannes Reinecke <hare@kernel.org>,
John Garry <john.g.garry@oracle.com>
Subject: [PATCH v2 0/4] scsi: replace __get_free_pages() with kmalloc()
Date: Sat, 04 Jul 2026 09:13:33 +0300 [thread overview]
Message-ID: <20260704-b4-scsi-v2-0-7d2d21a810de@kernel.org> (raw)
This is a (small) part of larger work of replacing page allocator calls
with kmalloc.
My initial intention a few month ago was to remove ugly casts [1], but then
willy pointed out that Linus objected to something like this [2] and it
looks like more than a decade old technical debt.
Largely, anything that doesn't need struct page (or a memdesc in the
future) should just use kmalloc() or kvmalloc() to allocate memory.
kmalloc() guarantees alignment, physical contiguity and working
virt_to_phys() and beside nicer API that returns void * on alloc and
doesn't require to know the allocation size on free, kmalloc() provides
better debugging capabilities than page allocator.
Another thing is that touching these allocation sites gives the reviewers
opportunity to see if a PAGE_SIZE buffer is actually needed or maybe
another size is appropriate.
For larger allocations that don't need physically contiguous memory
kvmalloc() can be a better option that __get_free_pages() because under
memory pressure it's is easier to allocate several order-0 pages than a
physically contiguous chunk with the same number of pages.
And last, but not least, removing needless calls to page allocator should
help with memdesc (aka project folio) conversion. There will be way less
places to audit to see if the user was actually using struct page.
Also in git:
https://git.kernel.org/pub/scm/linux/kernel/git/rppt/linux.git gfp-to-kmalloc/scsi
[1] https://lore.kernel.org/all/20251018093002.3660549-1-rppt@kernel.org/
[2] https://lore.kernel.org/all/CA+55aFwp4iy4rtX2gE2WjBGFL=NxMVnoFeHqYa2j1dYOMMGqxg@mail.gmail.com/
---
v2 changes:
* replace GFP_ATOMIC with GFP_NOIO in ipr driver
v1: https://patch.msgid.link/20260630-b4-scsi-v1-0-494fb37ebe7b@kernel.org
---
Mike Rapoport (Microsoft) (4):
scsi: target: file: use kmalloc() to allocate temporary protection buffer
scsi: proc: use kmalloc() in proc writers
scsi: ipr: use kmalloc() to allocate IPR dump buffer memory
scsi: sym53c8xx_2: replace __get_free_pages() with kmalloc()
drivers/scsi/ipr.c | 4 ++--
drivers/scsi/scsi_devinfo.c | 5 +++--
drivers/scsi/scsi_proc.c | 9 +++++----
drivers/scsi/sym53c8xx_2/sym_hipd.h | 4 ++--
drivers/target/target_core_file.c | 4 ++--
5 files changed, 14 insertions(+), 12 deletions(-)
---
base-commit: dc59e4fea9d83f03bad6bddf3fa2e52491777482
change-id: 20260611-b4-scsi-d0b0eb4895f4
--
Sincerely yours,
Mike.
next reply other threads:[~2026-07-04 6:13 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-04 6:13 Mike Rapoport (Microsoft) [this message]
2026-07-04 6:13 ` [PATCH v2 1/4] scsi: target: file: use kmalloc() to allocate temporary protection buffer Mike Rapoport (Microsoft)
2026-07-04 6:13 ` [PATCH v2 2/4] scsi: proc: use kmalloc() in proc writers Mike Rapoport (Microsoft)
2026-07-04 6:13 ` [PATCH v2 3/4] scsi: ipr: use kmalloc() to allocate IPR dump buffer memory Mike Rapoport (Microsoft)
2026-07-04 6:13 ` [PATCH v2 4/4] scsi: sym53c8xx_2: replace __get_free_pages() with kmalloc() Mike Rapoport (Microsoft)
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