Discard __GFP_ATOMIC
Status from this message: [merged mm-stable] mm-page_alloc-explicitly-define-how-__gfp_high-non-blocking-allocations-accesses-reserves.patch removed from -mm tree
Get series with b4
b4 am [email protected]Versions newest first · linked by author and title
- v3 Latest6 patches 3 repliesApplied 6/6
- v20 of 6 patches 0 repliesSuperseded
- v1 RFC6 patches 16 repliesSuperseded
Changes in v3 from the cover letter
o Non-blocking (GFP_NOWAIT) allocations get no reserve access (mhocko)
o __GFP_NOFAIL before OOM reserve access reduced (mhocko)
o Changelog clarifications (mhocko)
o Note that rt_task treatment to be deleted in changelog (mhocko)
o One ack dropped as the patch changed enough to invalidate it
Patches in v3 All 6 applied
| # | Subject and files | Size | Replies | Applied |
|---|---|---|---|---|
| 1/6 | mm/page_alloc: Rename ALLOC_HIGH to ALLOC_MIN_RESERVEmm/ mm/ | +7 | 0 replies | Applied |
| 2/6 | mm/page_alloc: Treat RT tasks similar to __GFP_HIGHmm/ | +1 | 0 replies | Applied |
| 3/6 | mm/page_alloc: Explicitly record high-order atomic allocations in alloc_flagsmm/ mm/ | +24 | 1 reply | Applied |
| 4/6 | mm/page_alloc: Explicitly define what alloc flags deplete min reservesmm/ mm/ | +25 | 0 replies | Applied |
| 5/6 | mm/page_alloc: Explicitly define how __GFP_HIGH non-blocking allocations accesses reservesmm/ mm/ | +29 | 2 replies | Applied |
| 6/6 | mm: discard __GFP_ATOMICDocumentation/ drivers/ include/ +5 more | +15 | 0 replies | Applied |
Reviews trailers per patch
All 6 patches have a Reviewed-by or Acked-by.
| Patch | Vlastimil Babka | Michal Hocko |
|---|---|---|
| 1/6 | A-b | A-b |
| 2/6 | A-b | A-b |
| 3/6 | A-b | A-b |
| 4/6 | A-b | A-b |
| 5/6 | A-b | A-b |
| 6/6 | A-b | A-b |
Trailers given in replies are filled; those carried in the patches from earlier versions are outlined with dashes.
Cover letter [PATCH 0/6 v3] Discard __GFP_ATOMIC
This replaces the "Discard __GFP_ATOMIC v2" series in mm-unstable. There are changelog and patch replacements that make -fix patches impractical.
Changelog since v2
o Non-blocking (GFP_NOWAIT) allocations get no reserve access (mhocko)
o __GFP_NOFAIL before OOM reserve access reduced (mhocko)
o Changelog clarifications (mhocko)
o Note that rt_task treatment to be deleted in changelog (mhocko)
o One ack dropped as the patch changed enough to invalidate it
Changelog since v1
o Split one patch (vbabka)
o Improve OOM reserve handling (vbabka)
o Fix __GFP_RECLAIM vs __GFP_DIRECT_RECLAIM (vbabka)
Neil's patch has been residing in mm-unstable as commit 2fafb4fe8f7a ("mm: discard __GFP_ATOMIC") for a long time and recently brought up again. Most recently, I was worried that __GFP_HIGH allocations could use high-order atomic reserves which is unintentional but there was no response so lets revisit -- this series reworks how min reserves are used, protects highorder reserves and then finishes with Neil's patch with very minor modifications so it fits on top.
There was a review discussion on renaming __GFP_DIRECT_RECLAIM to __GFP_ALLOW_BLOCKING but I didn't think it was that big an issue and is ortogonal to the removal of __GFP_ATOMIC.
There were some concerns about how the gfp flags affect the min reserves but it never reached a solid conclusion so I made my own attempt.
The series tries to iron out some of the details on how reserves are used. ALLOC_HIGH becomes ALLOC_MIN_RESERVE and ALLOC_HARDER becomes ALLOC_NON_BLOCK and documents how the reserves are affected. For example, ALLOC_NON_BLOCK (no direct reclaim) on its own allows 25% of the min reserve. ALLOC_MIN_RESERVE (__GFP_HIGH) allows 50% and both combined allows deeper access again. ALLOC_OOM allows access to 75%.
High-order atomic allocations are explicitly handled with the caveat that no __GFP_ATOMIC flag means that any high-order allocation that specifies GFP_HIGH and cannot enter direct reclaim will be treated as if it was GFP_ATOMIC.
Documentation/mm/balance.rst | 2 +- drivers/iommu/tegra-smmu.c | 4 +- include/linux/gfp_types.h | 12 ++-- include/trace/events/mmflags.h | 1 - lib/test_printf.c | 8 +-- mm/internal.h | 15 ++++- mm/page_alloc.c | 106 ++++++++++++++++++++------------- tools/perf/builtin-kmem.c | 1 - 8 files changed, 88 insertions(+), 61 deletions(-)
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