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1c53717440
Provide infrastructure to do a speculative fault (not holding mmap_sem). The not holding of mmap_sem means we can race against VMA change/removal and page-table destruction. We use the SRCU VMA freeing to keep the VMA around. We use the VMA seqcount to detect change (including umapping / page-table deletion) and we use gup_fast() style page-table walking to deal with page-table races. Once we've obtained the page and are ready to update the PTE, we validate if the state we started the fault with is still valid, if not, we'll fail the fault with VM_FAULT_RETRY, otherwise we update the PTE and we're done. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> [Manage the newly introduced pte_spinlock() for speculative page fault to fail if the VMA is touched in our back] [Rename vma_is_dead() to vma_has_changed() and declare it here] [Fetch p4d and pud] [Set vmd.sequence in __handle_mm_fault()] [Abort speculative path when handle_userfault() has to be called] [Add additional VMA's flags checks in handle_speculative_fault()] [Clear FAULT_FLAG_ALLOW_RETRY in handle_speculative_fault()] [Don't set vmf->pte and vmf->ptl if pte_map_lock() failed] [Remove warning comment about waiting for !seq&1 since we don't want to wait] [Remove warning about no huge page support, mention it explictly] [Don't call do_fault() in the speculative path as __do_fault() calls vma->vm_ops->fault() which may want to release mmap_sem] [Only vm_fault pointer argument for vma_has_changed()] [Fix check against huge page, calling pmd_trans_huge()] [Use READ_ONCE() when reading VMA's fields in the speculative path] [Explicitly check for __HAVE_ARCH_PTE_SPECIAL as we can't support for processing done in vm_normal_page()] [Check that vma->anon_vma is already set when starting the speculative path] [Check for memory policy as we can't support MPOL_INTERLEAVE case due to the processing done in mpol_misplaced()] [Don't support VMA growing up or down] [Move check on vm_sequence just before calling handle_pte_fault()] [Don't build SPF services if !CONFIG_SPECULATIVE_PAGE_FAULT] [Add mem cgroup oom check] [Use READ_ONCE to access p*d entries] [Replace deprecated ACCESS_ONCE() by READ_ONCE() in vma_has_changed()] [Don't fetch pte again in handle_pte_fault() when running the speculative path] [Check PMD against concurrent collapsing operation] [Try spin lock the pte during the speculative path to avoid deadlock with other CPU's invalidating the TLB and requiring this CPU to catch the inter processor's interrupt] [Move define of FAULT_FLAG_SPECULATIVE here] [Introduce __handle_speculative_fault() and add a check against mm->mm_users in handle_speculative_fault() defined in mm.h] Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com> Link: https://lore.kernel.org/lkml/1523975611-15978-19-git-send-email-ldufour@linux.vnet.ibm.com/ Bug: 161210518 Change-Id: I6a29e6edd9779bd34a9f7f4f6034e041a8487f30 Signed-off-by: Vinayak Menon <vinmenon@codeaurora.org> Signed-off-by: Charan Teja Reddy <charante@codeaurora.org>
How do I submit patches to Android Common Kernels
-
BEST: Make all of your changes to upstream Linux. If appropriate, backport to the stable releases. These patches will be merged automatically in the corresponding common kernels. If the patch is already in upstream Linux, post a backport of the patch that conforms to the patch requirements below.
- Do not send patches upstream that contain only symbol exports. To be considered for upstream Linux,
additions of
EXPORT_SYMBOL_GPL()require an in-tree modular driver that uses the symbol -- so include the new driver or changes to an existing driver in the same patchset as the export. - When sending patches upstream, the commit message must contain a clear case for why the patch is needed and beneficial to the community. Enabling out-of-tree drivers or functionality is not not a persuasive case.
- Do not send patches upstream that contain only symbol exports. To be considered for upstream Linux,
additions of
-
LESS GOOD: Develop your patches out-of-tree (from an upstream Linux point-of-view). Unless these are fixing an Android-specific bug, these are very unlikely to be accepted unless they have been coordinated with kernel-team@android.com. If you want to proceed, post a patch that conforms to the patch requirements below.
Common Kernel patch requirements
- All patches must conform to the Linux kernel coding standards and pass
script/checkpatch.pl - Patches shall not break gki_defconfig or allmodconfig builds for arm, arm64, x86, x86_64 architectures (see https://source.android.com/setup/build/building-kernels)
- If the patch is not merged from an upstream branch, the subject must be tagged with the type of patch:
UPSTREAM:,BACKPORT:,FROMGIT:,FROMLIST:, orANDROID:. - All patches must have a
Change-Id:tag (see https://gerrit-review.googlesource.com/Documentation/user-changeid.html) - If an Android bug has been assigned, there must be a
Bug:tag. - All patches must have a
Signed-off-by:tag by the author and the submitter
Additional requirements are listed below based on patch type
Requirements for backports from mainline Linux: UPSTREAM:, BACKPORT:
- If the patch is a cherry-pick from Linux mainline with no changes at all
- tag the patch subject with
UPSTREAM:. - add upstream commit information with a
(cherry picked from commit ...)line - Example:
- if the upstream commit message is
- tag the patch subject with
important patch from upstream
This is the detailed description of the important patch
Signed-off-by: Fred Jones <fred.jones@foo.org>
- then Joe Smith would upload the patch for the common kernel as
UPSTREAM: important patch from upstream
This is the detailed description of the important patch
Signed-off-by: Fred Jones <fred.jones@foo.org>
Bug: 135791357
Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
(cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
Signed-off-by: Joe Smith <joe.smith@foo.org>
- If the patch requires any changes from the upstream version, tag the patch with
BACKPORT:instead ofUPSTREAM:.- use the same tags as
UPSTREAM: - add comments about the changes under the
(cherry picked from commit ...)line - Example:
- use the same tags as
BACKPORT: important patch from upstream
This is the detailed description of the important patch
Signed-off-by: Fred Jones <fred.jones@foo.org>
Bug: 135791357
Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
(cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
[joe: Resolved minor conflict in drivers/foo/bar.c ]
Signed-off-by: Joe Smith <joe.smith@foo.org>
Requirements for other backports: FROMGIT:, FROMLIST:,
- If the patch has been merged into an upstream maintainer tree, but has not yet
been merged into Linux mainline
- tag the patch subject with
FROMGIT: - add info on where the patch came from as
(cherry picked from commit <sha1> <repo> <branch>). This must be a stable maintainer branch (not rebased, so don't uselinux-nextfor example). - if changes were required, use
BACKPORT: FROMGIT: - Example:
- if the commit message in the maintainer tree is
- tag the patch subject with
important patch from upstream
This is the detailed description of the important patch
Signed-off-by: Fred Jones <fred.jones@foo.org>
- then Joe Smith would upload the patch for the common kernel as
FROMGIT: important patch from upstream
This is the detailed description of the important patch
Signed-off-by: Fred Jones <fred.jones@foo.org>
Bug: 135791357
(cherry picked from commit 878a2fd9de10b03d11d2f622250285c7e63deace
https://git.kernel.org/pub/scm/linux/kernel/git/foo/bar.git test-branch)
Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
Signed-off-by: Joe Smith <joe.smith@foo.org>
- If the patch has been submitted to LKML, but not accepted into any maintainer tree
- tag the patch subject with
FROMLIST: - add a
Link:tag with a link to the submittal on lore.kernel.org - add a
Bug:tag with the Android bug (required for patches not accepted into a maintainer tree) - if changes were required, use
BACKPORT: FROMLIST: - Example:
- tag the patch subject with
FROMLIST: important patch from upstream
This is the detailed description of the important patch
Signed-off-by: Fred Jones <fred.jones@foo.org>
Bug: 135791357
Link: https://lore.kernel.org/lkml/20190619171517.GA17557@someone.com/
Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
Signed-off-by: Joe Smith <joe.smith@foo.org>
Requirements for Android-specific patches: ANDROID:
- If the patch is fixing a bug to Android-specific code
- tag the patch subject with
ANDROID: - add a
Fixes:tag that cites the patch with the bug - Example:
- tag the patch subject with
ANDROID: fix android-specific bug in foobar.c
This is the detailed description of the important fix
Fixes: 1234abcd2468 ("foobar: add cool feature")
Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
Signed-off-by: Joe Smith <joe.smith@foo.org>
- If the patch is a new feature
- tag the patch subject with
ANDROID: - add a
Bug:tag with the Android bug (required for android-specific features)
- tag the patch subject with